Phosphorylation of ubiquitin-activating enzyme in cultured cells.
AUTOR(ES)
Cook, J C
RESUMO
Ubiquitin-activating enzyme, E1, is the first enzyme in the pathway leading to formation of ubiquitin-protein conjugates. E1 exists as two isoforms in human cells which are separable by electrophoresis. These isoforms migrate with apparent molecular sizes of 110 kDa and 117 kDa in SDS/polyacrylamide gels. Immunoprecipitation of E1 from lysates of HeLa cells metabolically labeled with [32P]phosphate indicated the presence of a phosphorylated form of E1 which migrates at 117 kDa. Phospho amino acid analysis identified serine as the phosphorylated residue in E1. Phosphorylated E1 was also detected in normal and transformed cells from another human cell line. Phosphatase-catalyzed dephosphorylation of E1 in vitro did not eliminate the 117-kDa E1 isoform detected by Coomassie staining after SDS/polyacrylamide gel electrophoresis, thereby demonstrating that phosphorylation is not the sole structural feature differentiating the isoforms of E1. These observations suggest new hypotheses concerning mechanisms of metabolic regulation of the ubiquitin conjugation pathway.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=42185Documentos Relacionados
- Immunoelectron microscopic localization of the ubiquitin-activating enzyme E1 in HepG2 cells.
- UBA 1: an essential yeast gene encoding ubiquitin-activating enzyme.
- Association of ubiquitin-activating enzyme with HeLa cell chromosomes during mitosis.
- Molecular cloning, sequence, and tissue distribution of the human ubiquitin-activating enzyme E1.
- Molecular cloning, sequence, and tissue distribution of the human ubiquitin-activating enzyme E1.