Identifying changes in the synaptic proteome of cirrhotic alcoholic superior frontal gyrus.

Hepatic complications are a common side-effect of alcoholism. Without the detoxification capabilities of the liver, alcohol misuse induces changes in gene and protein expression throughout the body. A global proteomics approach was used to identify these protein changes in the brain. We utilised human autopsy tissue from the superior frontal gyrus (SFG) of six cirrhotic alcoholics, six alcoholics without comorbid disease, and six non-alcoholic non-cirrhotic controls. Synaptic proteins were isolated and used in two-dimensional differential in-gel electrophoresis coupled with mass spectrometry. Many expression differences were confined to one or other alcoholic sub-group. Cirrhotic alcoholics showed 99 differences in protein expression levels from controls, of which half also differed from non-comorbid alcoholics. This may reflect differences in disease severity between the sub-groups of alcoholics, or differences in patterns of harmful drinking. Alternatively, the protein profiles may result from differences between cirrhotic and non-comorbid alcoholics in subjects' responses to alcohol misuse. Ten proteins were identified in at least two spots on the 2D gel; they were involved in basal energy metabolism, synaptic vesicle recycling, and chaperoning. These post-translationally modified isoforms were differentially regulated in cirrhotic alcoholics, indicating a level of epigenetic control not previously observed in this disorder.

Characterization of ATDRG1, a member of a new class of GTP-binding proteins in plants.

We report the initial characterization of an Arabidopsis thaliana cDNA (atdrg1), a member of a new class of GTP-binding proteins (G-proteins) in plants. The predicted ATDRG1 protein contains all five structural motifs characteristic of the G-protein superfamily. Apart from these motifs, the amino acid sequence differs substantially from all known G-proteins except for a recently discovered new family named developmentally regulated G-proteins (DRGs). Sequences closely related to atdrg1 are found in species as distant as human (80% amino acid conservation), Drosophila (74%), yeast (77%) and Caenorhabditis elegans (77%). The remarkable evolutionary conservation of these proteins suggests an important, but as yet unclear role. Phylogenetic analysis of the available homologous sequences strongly suggests a diphyletic origin of the eukaryotic DRG proteins. Northern analysis shows high levels of atdrg1 mRNA in all Arabidopsis tissues studied, and homologues of atdrg1 are present throughout the plant kingdom. In situ hybridization reveals that atdrg1 is highly expressed in actively growing tissues and reproductive organs. Southern analysis indicates the presence of either one or two copies of atdrg1 in the Arabidopsis genome. Immunolocalization studies show that the protein is present in cytoplasmic vesicles found mainly in actively growing tissues suggesting a putative role for ATDRG1 in either the regulation of vesicle transport or the regulation of enzymes involved in storage protein processing.