RESUMEN
A vincristine-resistant lymphoma cell line (HOB1/VCR1.0) that is resistant to 1.0 microM of vincristine has been established from a human immunoblastic B lymphoma cell line, HOB1. HOB1/VCR1.0 cells demonstrated the typical multidrug resistant phenotypes. Using two-dimensional gel electrophoresis, we discovered one protein with a molecular mass of 22 kDa and pI 5.7 that was overexpressed in HOB1/VCR1.0 cells. This protein was purified to the degree of apparent homogeneity by preparative isoelectric focusing and sodium dodecylsulfate-polyacrylamide gel electrophoresis. The identification of this protein with sorcin was revealed by comparing the internal amino acid sequence of three Lys-C digested peptides from the purified protein with the sequence previously determined for hamster sorcin. The complete primary structure of the human sorcin was deduced from nucleotide sequence analysis of its cDNA clones. It is composed of 198 amino acid residues with a calculated molecular weight of 21,676, and its sequence is highly similar to that of hamster sorcin (95%). Direct-binding assay with calcium showed that human sorcin is a calcium-binding protein with four 'E-F hand' structures typical of calcium-binding sites. Like the sorcin of hamster, two of the calcium-binding sites of human sorcin contain putative recognition sites for cAMP-dependent protein kinase. Southern and Northern blot analyses showed that the human sorcin gene was greatly amplified and overexpressed in resistant HOB1/VCR1.0 cells but not detected in the parental HOB1 cells. The overproduction of this protein in resistant cells implies that sorcin plays a role in expression of the resistant phenotype.
Asunto(s)
Proteínas de Unión al Calcio/genética , Linfoma de Células B/genética , Linfoma Inmunoblástico de Células Grandes/genética , Proteínas de Neoplasias/genética , Vincristina/farmacología , Secuencia de Aminoácidos , Animales , Secuencia de Bases , Calcio/metabolismo , Proteínas de Unión al Calcio/aislamiento & purificación , Clonación Molecular , Cricetinae , ADN Complementario , Resistencia a Medicamentos , Amplificación de Genes , Humanos , Linfoma de Células B/metabolismo , Linfoma de Células B/patología , Linfoma Inmunoblástico de Células Grandes/metabolismo , Linfoma Inmunoblástico de Células Grandes/patología , Datos de Secuencia Molecular , Proteínas de Neoplasias/aislamiento & purificación , Unión Proteica , Homología de Secuencia de Aminoácido , Células Tumorales CultivadasRESUMEN
A full-length cDNA clone encoding a putative copper/zinc-superoxide dismutase (SOD) of sweet potato, Ipomoea batatas (L.) Lam. cv Tainong 57, was isolated from a cDNA library constructed in lambda gt10 from tuber root mRNA. Nucleotide sequence analysis of this cDNA clone revealed that it comprises a complete open reading frame coding for 152 amino acid residues. The deduced amino acid sequence showed higher homology (78-86%) with the sequence of the cytosolic SOD than that of the chloroplast SOD from other plant species. The residues required for coordinating copper and zinc are conserved as they are among all reported Cu/Zn-SOD sequences. In addition, it lacks recognizable plastic or mitochondrial targeting sequences. These data suggest that the isolated sweet potato clone encodes a cytosolic Cu/Zn-SOD.
Asunto(s)
Solanum tuberosum/enzimología , Superóxido Dismutasa/genética , Secuencia de Aminoácidos , Secuencia de Bases , Clonación Molecular , Citosol/enzimología , Cartilla de ADN/química , ADN Complementario/genética , Datos de Secuencia Molecular , Alineación de Secuencia , Homología de Secuencia de AminoácidoRESUMEN
The protective activity against carbon tetrachloride induced hepatotoxicity of several phenolic flavan-3-ols and their derivatives has been assessed. Our research showed that monomers possessing a pyrogallol moiety as the B-ring had greater activity and this was not directly related to the stereo-chemistry of the hydroxyl group at C-3 in the flavan unit. However, when a galloyl group was linked to the hydroxyl group to form a gallate, this product exhibited markedly more activity than other analogs. These results suggest that the antihepatotoxic activity of phenolic flavan-3-ols and their derivatives seem to be related to the galloylation at the C-3 hydroxyl group in the flavan skeleton rather than the structure of another moiety or the degree of condensation.