[Carney triad]. / Carneyho trias.

Carney triad is a synchronous or metachronous association of gastric gastrointestinal stromal tumors (GIST), pulmonary chondroma and extra-adrenal paraganglioma. The majority of patients have only one or two components of the triad, all three tumors being found in only about 2% of the patients at the time of the first diagnosis. The most common combination is gastric and pulmonary tumors. We report a case of Carney triad which was diagnosed at Masaryk Memorial Cancer Institute. A 57-year-old female patient with a history of gastric resection for leiomyosarcoma at the age of 14 and with an unclear pulmonary lesion evident on chest X-ray since as early as 2003. She was referred to our Clinic of Comprehensive Cancer Care after being diagnosed with unspecified tumors of the stomach, the left retroperitoneum and two liver metastases. Biopsy of the retroperitoneal mass was performed and histological examination showed pheochromocytoma. The patient underwent resection of the retroperitoneal tumor and wedge resection of the gastric tumor, left hemihepatectomy and left adrenalectomy (in two separate operations). The excised gastric tumor was a gastrointestinal stromal tumor (GIST) with a low risk of malignancy. Analysis of a liver specimen, however, showed two GIST metastases. No pathology was found in the left adrenal gland and the retroperitoneal tumor was positive for chromogranin A. Paraganglioma was thus diagnosed. Subsequently, mutational analysis of genes coding for succinate dehydrogenase subunits B, C and D (SDHB, SDHC, SDHD) and analysis of DNA methylation at the gene locus of SDHC was made. Carney triad was thus confirmed and the unclear pulmonary lesion could be described as benign chondroma. This report demonstrates the difficulty in distinguishing between Carney triad and Carney-Stratakis syndrome. Molecular information should improve the diagnosis of Carney triad.Key words: Carney triad - GIST pulmonary chondroma extraadrenal paragangliomaCarney-Stratakis syndrome.

Long term experience of patients with unresectable or metastatic KIT positive gastrointestinal stromal tumours.

A retrospective analysis of consecutive patients (183 in total, of which 105 were males and 78 females) with gastrointestinal stromal tumour (GIST) was performed. The mean age was 61 years, median age 64 years. The most frequent localization of the tumour was stomach in 74 patients (40.4 %) and the small intestine in 46 patients (25.1 %). Two or more different synchronous or metachronous cancers occurred in 34 (18.6 %) patients with histologically confirmed GIST. Ninety-six patients were treated with imatinib mesylate in palliative setting during the course of their disease. The therapy was finished in 60 patients and 36 patients have been treated so far. The median progression-free survival reached 32.9 months in the group of 96 patients treated with imatinib. The median overall survival in the group of 96 patients treated for metastatic disease reached 77 months. Two-year and 5-year survival was 85.2 % and 63.1 %, respectively. The second-line therapy with sunitinib malate was administered in 37 patients, of which 31 finished and 6 continued in the therapy. The median progression free survival and median survival since the sunitinib therapy initiation reached 8.4 and 22.1 months, respectively (Tab. 2, Fig. 2, Ref. 16).

Does folic acid supplementation rescue defects in ECE-1-deficient mouse embryos?

Endothelin (ET) signalling is essential for normal embryonic development. Disruption of this pathway leads to defects in the development of subsets of cranial and cephalic neural crest derivatives. Endothelin-converting enzyme 1 (ECE-1) is a ratelimiting step in the biosynthesis of ET-1. Recently, there has been considerable interest in the protective role of folic acid (FA) against congenital anomalies via increasing the expression of ET-1. We have tested whether FA supplementation can rescue craniofacial and cardiac defects observed in the ECE1-/- embryos. ECE1+/- mice were caged together to obtain litters containing embryos of all possible genotypes. The treatment group had the diet supplemented with 20 mg/kg of FA from the day of discovery of the vaginal plug. FA supplementation did not result in modified proportions of the genotypes, indicating no rescue of the embryonic mortality. There was also no effect on the litter size. Craniofacial and cardiac defects were likewise identical in the ECE1-/- embryos of both groups. There was a mild but significant reduction in the embryo size in wild-type and heterozygous FA-supplemented embryos, and there were haemorrhages in the wild-type supplemented embryos at ED14.5. Expression of ET receptor A detected by immunohistochemistry was up-regulated in the ECE1-/- embryos, but FA supplementation had no effects on the distribution of staining intensity. We conclude that FA is not able to rescue the phenotype in this model, suggesting an alternative pathway for its action. These results also caution against indiscriminate use of dietary supplements in attempts to prevent congenital anomalies.

Isolation and characterization of neural crest stem cells from adult human hair follicles.

Neural crest (NC) is a transient embryonic tissue, whose cells are motile and multipotent until they reach their destination and differentiate according to microenvironmental cues into a variety of cell types. However, a subpopulation of these cells remains multipotent. They were found, among other locations, in a bulge of adult murine whisker follicle and were designated epidermal neural crest stem cells (EPI-NCSCs). The aim of this work is to ascertain whether the EPI-NCSCs could be isolated from human hair follicles as well. Due to their exceptional properties, they could represent potential candidates for stem cell therapy. The presented work focuses on the isolation and characterization of EPI-NCSCs from human skin. We obtained a population of cells that expressed markers of NC, NC progeny and general stem cell markers. After prolonged cultivation, the subpopulation of cells spontaneously differentiated into some of NC derivatives, i.e. neurons, smooth muscle cells and Schwann cell progenitors. Targeted differentiation with neuregulin 1 highly increased the number of Schwann cells in the culture. Human EPI-NCSCs could also grow under non-adherent conditions and form 3-dimensional spheres. Microarray analysis was performed and gene profile of human EPI-NCSCs was compared with the list of key genes of murine EPI-NCSCs and the list of genes up-regulated in newly induced NC cells. This revealed 94% and 88% similarity, respectively. All presented results strongly support the NCSC identity and multipotency of isolated human cells. These cells could thus be used in regenerative medicine, especially because of the easy accessibility of donor tissue.

Genetic testing and prevention of hereditary cancer at the MMCI--over 10 years of experience.

Hereditary cancer syndromes are frequently seen in young cancer patients and patients with a positive family history. Genetic testing is important for the identification of high-risk individuals, and for the early introduction of specialized preventive care or prophylactic surgeries. High-risk tumour suppressor genes (BRCA1 and BRCA2) and DNA repair genes (MLH1, MSH2 and MSH6) are responsible for a substantial part of hereditary breast, ovarian and colorectal cancer. Other hereditary cancers are seen less frequently, but genetic testing has increased for many other site-specific cancers and complex syndromes. Genetic centres and molecular genetic laboratories are located mostly within university or regional hospitals. Some genetic centres are private. It is highly recommended (Czech Society for Medical Genetics) that all laboratories are accredited according to ISO 15,189 and that genetic testing of hereditary cancer syndromes is indicated by medical geneticists. The indication criteria and prevention strategies were published in Supplement 22 of Clinical Oncology 2009 (in Czech). Preventive care for high-risk individuals is organized by thirteen Oncology Centres, which provide most of the oncology care in the Czech Republic. Genetic testing and preventive care for high-risk individuals and mutation carriers is covered by health insurance. The molecular genetic laboratory at the MMCI provides molecular genetic testing of BRCA1, BRCA2, CHEK2 for hereditary breast/ovarian cancer, MLH1, MSH2, MSH6 for Lynch syndrome,TP53 for Li-Fraumeni syndrome, CDKN2A for familial malignant melanoma syndrome and CDH1 gene for hereditary diffuse gastric cancer. Other syndromes are tested in specialized laboratories elsewhere.The use of genetic testing is increasing because of more frequent referrals from oncologists and other specialists and the increasing variety of genes tested. However, in some patients the testing is not recommended and other family members are dying because of the late diagnosis of hereditary syndrome. Greater awareness of the importance of genetic testing in oncology is needed.

Genetic analysis of collagen Q: roles in acetylcholinesterase and butyrylcholinesterase assembly and in synaptic structure and function.

Acetylcholinesterase (AChE) occurs in both asymmetric forms, covalently associated with a collagenous subunit called Q (ColQ), and globular forms that may be either soluble or membrane associated. At the skeletal neuromuscular junction, asymmetric AChE is anchored to the basal lamina of the synaptic cleft, where it hydrolyzes acetylcholine to terminate synaptic transmission. AChE has also been hypothesized to play developmental roles in the nervous system, and ColQ is also expressed in some AChE-poor tissues. To seek roles of ColQ and AChE at synapses and elsewhere, we generated ColQ-deficient mutant mice. ColQ-/- mice completely lacked asymmetric AChE in skeletal and cardiac muscles and brain; they also lacked asymmetric forms of the AChE homologue, butyrylcholinesterase. Thus, products of the ColQ gene are required for assembly of all detectable asymmetric AChE and butyrylcholinesterase. Surprisingly, globular AChE tetramers were also absent from neonatal ColQ-/- muscles, suggesting a role for the ColQ gene in assembly or stabilization of AChE forms that do not themselves contain a collagenous subunit. Histochemical, immunohistochemical, toxicological, and electrophysiological assays all indicated absence of AChE at ColQ-/- neuromuscular junctions. Nonetheless, neuromuscular function was initially robust, demonstrating that AChE and ColQ do not play obligatory roles in early phases of synaptogenesis. Moreover, because acute inhibition of synaptic AChE is fatal to normal animals, there must be compensatory mechanisms in the mutant that allow the synapse to function in the chronic absence of AChE. One structural mechanism appears to be a partial ensheathment of nerve terminals by Schwann cells. Compensation was incomplete, however, as animals lacking ColQ and synaptic AChE failed to thrive and most died before they reached maturity.

Reduced inducibility of SOCS3 by interferon gamma associates with higher resistance of human breast cancer lines as compared to normal mammary epithelial cells.

The resistance to interferons (IFNs) limits their anticancer therapeutic efficacy. Here we studied the antiproliferative effect of interferon gamma in relation to SOCS3 expression in a panel of breast cancer cell lines and normal mammary epithelial cells. Compared to normal cells most breast cancer lines (7/8) were highly resistant to IFN-gamma. Using Northern blot and real time RT-PCR we investigated transcription of SOCS3 genes. All normal epithelial cells (4/4) showed SOCS3 induction (2-14 fold) while most breast cancer lines did not or weakly activated SOCS3 after the interferon gamma treatment. Among the cancer lines, the MDA-MB-468 cells showed increased sensitivity to IFN-gamma and relatively high level of SOCS3 induction (2-3 fold). Together, there was a good correlation

Towards the molecular biology of cell adhesion in Drosophila.

The characterization of extracellular matrix molecules and their putative receptors is rapidly evolving in Drosophila. Where corresponding vertebrate and Drosophila extracellular proteins have been identified they are very similar with respect to their structural properties, suggesting a high degree of conservation during evolution. By contrast, indications for components homologous to vertebrate cell-cell adhesion molecules are still very sparse. Studies on the regulation of the Drosophila genes encoding cell adhesion molecules that are involved in general basic functions during morphogenesis, together with a knowledge of the function of the genes responsible for pattern formation, should lead towards a more complete understanding of the organism's developmental program.

Preoperative radiotherapy and concomitant capecitabine treatment induce thymidylate synthase and thymidine phosphorylase mRNAs in rectal carcinoma.

This work is intended to study the effect of preoperative capecitabine and radiotherapy treatment on the levels of thymidylate synthase (TS), thymidine phosphorylase (TP) and dihydropyrimidine dehydrogenase (DPD) mRNAs in rectal carcinoma. 55 patients with locally advanced rectal carcinoma (cT3-4, N0, M0 or cT2-4,N+, M0) were treated with capecitabine 825 mg/m2 twice a day and pelvic radiotherapy 1,8 Gy daily up to cumulative dose of 45 Gy, boosting up to 50,4 Gy. Patients underwent surgery 6th week after the completion of chemoradiotherapy. Biopsies of rectal carcinoma were taken before starting therapy and 14 days after its cesation. Biopsies were examined for TS, DPD and TP mRNA levels. CEA in serum was examined to monitor relapses. Both TP and TS mRNA increase two weeks after starting therapy (p<0,001). TP mRNA median levels were elevated 2,3x after starting therapy. Moreover responders exhibit 1,5x higher induction than non-responders both before and after starting therapy, but difference is significant before therapy only (p=0,017). Non-responders have most frequent TS induction. Complete remission was observed in 17% and substantial responses with microscopic residuum only in additional 19% of cases were achieved. The pathologic downstaging rate was 76%. Our data show that TS and TP mRNA are induced by preoperative chemoradiotherapy in both responders and nonresponders. TP induction is in accordance with the expected role of TP in the activation of capecitabine and the known promoting role of TP in tissue fibrosis frequently associated with tumor regression.

[Aeromonas spp. as the causative agent of acute diarrhoea in children under 1 year of age]. / Aeromonas spp. jako puvodce akutních prujmu detí do jednoho roku.

STUDY OBJECTIVE: To establish whether there is a link between cases of acute watery diarrhoea and a specific Aeromonas species. MATERIALS AND METHODS: Eight strains studied were identified as aeromonads and were further characterized by biochemical tests, fatty acid analysis and ribotyping. RESULTS: Aeromonads were isolated repeatedly from stool specimens of four children under one year of age with acute diarrhoea, two of whom were admitted to hospital. Of eight isolated aeromonads strains six were identified as A. caviae, one was classified into A. veronii bv. sobria and one could not be identified to the species level. Only two A. caviae strains from one patient were found to be identical by ribotyping while the Aeromonas species (strains) isolated from the other cases differed from one another. Contaminated fresh water, contaminated food and contact with travellers with imported diarrhoea were identified as probable sources of infection. CONCLUSION: Four cases of acute gastroenteritis in small children document that aeromonads are not rare and can cause serious health problems. However, epidemiological links remain unclear. We did not prove correlation between the four serious cases of acute diarrhoea and specific Aeromonas species but the results suggest the predominant role of A. caviae.

Physiological role of FGF signaling in growth and remodeling of developing cardiovascular system.

Fibroblast growth factor (FGF) signaling plays an important role during embryonic induction and patterning, as well as in modulating proliferative and hypertrophic growth in fetal and adult organs. Hemodynamically induced stretching is a powerful physiological stimulus for embryonic myocyte proliferation. The aim of this study was to assess the effect of FGF2 signaling on growth and vascularization of chick embryonic ventricular wall and its involvement in transmission of mechanical stretch-induced signaling to myocyte growth in vivo. Myocyte proliferation was significantly higher at the 48 h sampling interval in pressure-overloaded hearts. Neither Western blotting, nor immunohistochemistry performed on serial paraffin sections revealed any changes in the amount of myocardial FGF2 at that time point. ELISA showed a significant increase of FGF2 in the serum. Increased amount of FGF2 mRNA in the heart was confirmed by real time PCR. Blocking of FGF signaling by SU5402 led to decreased myocyte proliferation, hemorrhages in the areas of developing vasculature in epicardium and digit tips. FGF2 synthesis is increased in embryonic ventricular cardiomyocytes in response to increased stretch due to pressure overload. Inhibition of FGF signaling impacts also vasculogenesis, pointing to partial functional redundancy in paracrine control of cell proliferation in the developing heart.

Differences in expression of acetylcholinesterase and collagen Q control the distribution and oligomerization of the collagen-tailed forms in fast and slow muscles.

The collagen-tailed forms of acetylcholinesterase (AChE) are accumulated at mammalian neuromuscular junctions. The A(4), A(8), and A(12) forms are expressed differently in the rat fast and slow muscles; the sternomastoid muscle contains essentially the A(12) form at end plates, whereas the soleus muscle also contains extrajunctional A(4) and A(8) forms. We show that collagen Q (ColQ) transcripts become exclusively junctional in the adult sternomastoid but remain uniformly expressed in the soleus. By coinjecting Xenopus oocytes with AChE(T) and ColQ mRNAs, we reproduced the muscle patterns of collagen-tailed forms. The soleus contains transcripts ColQ1 and ColQ1a, whereas the sternomastoid only contains ColQ1a. Collagen-tailed AChE represents the first evidence that synaptic components involved in cholinergic transmission may be differently regulated in fast and slow muscles.

Lack of STAT 1 phosphorylation at TYR 701 by IFNgamma correlates with disease outcome in melanoma patients.

STAT 1, a member of signal transducer and transcription activator family has been implicated as key downstream mediator of interferon (IFN) signaling. Its functional activation requires phosphorylation at Tyr 701 and Ser 727 residues. Various STAT abnormalities have been found in cancer cells but their relation to oncogenesis, tumor behavior and disease outcome remains mostly unknown. We have examined the inducibility of STAT 1 phosphorylation by IFN alpha/gamma in primary cultures established from melanoma lymph node metastases at first progression and correlated our results with disease outcome and overall survival. Forty-four patients at clinical stage I-III at initial diagnosis entered the study. STAT 1 inducibility of phosphorylation by IFNs was assessed in melanoma cell lysates by means of standard immunoprecipitation and Western blotting using polyclonal and monoclonal antibodies. Lack of STAT 1 phosphorylation at Ser 727 after either IFN was recorded in 75% of patients, however, no correlations with disease evolution could be proved. In contrast, STAT 1 phosphorylation response at Tyr 701 after IFNalpha occurred in 13 (29.5%) and after IFNgamma in 32 (73%) patients. Inducibility of STAT 1 activation at Tyr 701 but not at Ser 727 driven by IFNgamma but not by IFNalpha significantly and unfavorably [corrected] influenced disease- free interval and overall survival. In conclusion, these results show that the absence of IFNgamma inducibility of STAT 1 phosphorylation at Tyr 701 positively correlates with disease outcome in malignant melanoma patients and may represent new independent prognostic marker.

In vitro differences of neonatal and later postnatal keratinocytes and dermal fibroblasts.

Skin healing process is postnatally always associated with scarring of various extent. Based on the clinical experience of plastic surgeons, the healing after lip cleft reconstruction is surprisingly almost scar-less when it is carried out within a few first days after birth. This phenomenon is not seen in delayed cases. In order to decipher causative mechanism, we have isolated and studied principal cell populations, keratinocytes and fibroblast, from residual tissue samples after reconstructive operation (N=39) performed at various age (0-9 years). These cells play the pivotal role in the healing and that is why we focused on description of their phenotype and also functionality with respect to age. We have identified a population of remarkably small cells in explants from newborns (day 0-10). These small cells were strongly positive for markers of low differentiated keratinocytes, keratin-8 and -19, and moreover also for vimentin. In the explants cultures from older babies this population was missing. Fibroblasts from newborns and older patients differed namely in terms of nestin expression and also in the production of extracellular matrix components. We conclude that in vitro described properties of keratinocytes and fibroblasts in newborns could participate on the almost scar-less wound healing in earliest neonatal period.

Role of c-Myb in chondrogenesis.

The Myb locus encodes the c-Myb transcription factor involved in controlling a broad variety of cellular processes. Recently, it has been shown that c-Myb may play a specific role in hard tissue formation; however, all of these results were gathered from an analysis of intramembranous ossification. To investigate a possible role of c-Myb in endochondral ossification, we carried out our study on the long bones of mouse limbs during embryonic development. Firstly, the c-myb expression pattern was analyzed by in situ hybridization during endochondral ossification of long bones. c-myb positive areas were found in proliferating as well as hypertrophic zones of the growth plate. At early embryonic stages, localized expression was also observed in the perichondrium and interdigital areas. The c-Myb protein was found in proliferating chondrocytes and in the perichondrium of the forelimb bones (E14.5-E17.5). Furthermore, protein was detected in pre-hypertrophic as well as hypertrophic chondrocytes. Gain-of-function and loss-of-function approaches were used to test the effect of altered c-myb expression on chondrogenesis in micromass cultures established from forelimb buds of mouse embryos. A loss-of-function approach using c-myb specific siRNA decreased nodule formation, as well as downregulated the level of Sox9 expression, a major marker of chondrogenesis. Transient c-myb overexpression markedly increased the formation of cartilage nodules and the production of extracellular matrix as detected by intense staining with Alcian blue. Moreover, the expression of early chondrogenic genes such as Sox9, Col2a1 and activity of a Col2-LUC reporter were increased in the cells overexpressing c-myb while late chondrogenic markers such as Col10a1 and Mmp13 were not significantly changed or were downregulated. Taken together, the results of this study demonstrate that the c-Myb transcription factor is involved in the regulation and promotion of endochondral bone formation.

Expression of a bovine vesicular monoamine transporter in COS cells.

Catecholamines are accumulated in vesicles by a proton gradient-dependent transport, which has mostly been studied in bovine chromaffin granules. The full sequence of a cDNA encoding a vesicular transporter from bovine chromaffin cells, bVMAT2, was recently reported. We now present an analysis of bVMAT2, expressed in transfected COS cells. Comparing the binding of a labelled ligand, [3H]TBZOH, and the rate of uptake, we find a much lower molecular turnover number than in chromaffin granules, probably indicating that a majority of expressed transporters are correctly folded and possess the ligand binding site but cannot actively transport monoamines because they are located in compartments which do not possess a proton gradient. The substrate specificity of uptake and its pharmacological sensitivity to various inhibitors closely resemble those previously observed in chromaffin granules. These results suggest that VMAT2 is the major transporter in bovine adrenal glands, and raise the question of the significance of the second related transporter, VMAT1, which is also expressed in this tissue.

Expression and regulation of the bovine vesicular monoamine transporter gene.

In monoaminergic cells, the neurotransmitter is accumulated into secretory or synaptic vesicles by a tetrabenazine- and reserpine-sensitive transporter, catalyzing an H+/monoamine antiport. The major vesicular monoamine transporter from bovine chromaffin cells was cloned, using sequences common to adrenal medulla and brain rat vesicular monoamine transporters. Its identity was confirmed by peptide sequences, determined from the purified protein. Surprisingly, the bovine adrenal medulla sequence, bVMAT2, is more related to the transporter from human and rat brain than to that from rat adrenal medulla. PCR amplification showed that bVMAT2 is expressed in both adrenal medulla and brain, in contrast with the situation reported in rats, where distinct genes appear to be expressed in brain (SVAT or MAT, now renamed rVMAT2) and in the adrenal medulla (CGAT, now renamed rVMAT1). In bovine chromaffin cells, long-term depolarization by KCl resulted in an increase in the level of bVMAT2 mRNA, in agreement with the previously observed increase in the transporter binding sites, suggesting that a coupling between stimulation, secretion and synthesis changes the composition of the secretory granule membrane.

Acetylcholinesterase: C-terminal domains, molecular forms and functional localization.

Acetylcholinesterase (AChE) possesses short C-terminal peptides that are not necessary for catalytic activity. These peptides belong to different classes (R, H, T, S) and define the post-translational processing and targeting of the enzyme. In vertebrates, subunits of type H (AChEH) and of type T (AChET) are the most important: AChEH subunits produce glycolipid (GPI)-anchored dimers and AChET subunits produce hetero-oligomeric forms such as membrane-bound tetramers in the mammalian brain (containing a 20 kDa hydrophobic protein) and asymmetric collagen-tailed forms in neuromuscular junctions (containing a specific collagen, ColQ). The T peptide allows the formation of tetrameric assemblies with a proline-rich attachment domain (PRAD) of collagen ColQ. These complex molecular structures condition the functional localization of the enzyme in the supramolecular architecture of cholinergic synapses.

Development of the neuromuscular junction: genetic analysis in mice.

Formation of the skeletal neuromuscular junction is a multi-step process that requires communication between the nerve and muscle. Studies in many laboratories have led to identification of factors that seem likely to mediate these interactions. 'Knock-out' mice have now been generated with mutations in several genes that encode candidate transsynaptic messengers and components of their effector mechanisms. Using these mice, it is possible to test hypotheses about the control of synaptogenesis. Here, we review our studies on neuromuscular development in mutant mice lacking agrin alpha CGRP, rapsyn, MuSK, dystrophin, dystrobrevin, utrophin, laminin alpha 5, laminin beta 2, collagen alpha 3 (IV), the acetylcholine receptor epsilon subunit, the collagenous tail of acetylcholinesterase, fibroblast growth factor-5, the neural cell adhesion molecule, and tenascin-C.

The polymorphism of acetylcholinesterase: post-translational processing, quaternary associations and localization.

The molecular forms of acetylcholinesterase (AChE) correspond to various quaternary structures and modes of anchoring of the enzyme. In vertebrates, these molecules are generated from a single gene: the catalytic domain may be associated with several types of C-terminal peptides, that define distinct types of catalytic subunits (AChE(S), AChE(H), AChE(T)) and determine their post-translational maturation. AChE(S) generates soluble monomers, in the venom of Elapid snakes. AChE(H) generates GPI-anchored dimers, in Torpedo muscles and on mammalian blood cells. AChE(T) is the only type of catalytic subunit that exists in all vertebrate cholinesterases; it produces the major forms in adult brain and muscle. AChE(T) generates multiple structures, ranging from monomers and dimers to collagen-tailed and hydrophobic-tailed forms, in which catalytic tetramers are associated with anchoring proteins that attach them to the basal lamina or to cell membranes. In the collagen-tailed forms, AChE(T) subunits are associated with a specific collagen, ColQ, which is encoded by a single gene in mammals. ColQ contains a short peptidic motif, the proline-rich attachment domain (PRAD), that triggers the formation of AChE(T) tetramers, from monomers and dimers. The critical feature of this motif is the presence of a string of prolines, and in fact synthetic polyproline shows a similar capacity to organize AChE(T) tetramers. Although the COLQ gene produces multiple transcripts, it does not generate the hydrophobic tail. P, which anchors AChE in mammalian brain membranes. The coordinated expression of AChE(T) subunits and anchoring proteins determines the pattern of molecular forms and therefore the localization and functionality of the enzyme.