Metabolic turnover of phosphorylation sites in simian virus 40 large T antigen.
Four (groups of) phosphorylation sites exist in the large T antigen of simian virus 40, and they involve at least two serine and two threonine residues (Van Roy et al. J. Virol. 45:315-331, 1983). All the phosphorylation sites were found to be modified and again dephosphorylated at discrete rates, with phosphoserine residues having the highest turnover rate. The measured half-lives ranged between 3 h (for the carboxy-terminal phosphoserine site) and 5.5 h (for the amino-terminal phosphothreonine site). The influence of four temperature-sensitive A mutations on phosphorylation of large T antigen was also examined. At restrictive temperature, phosphorylation of the carboxy-terminal phosphoserine in mutated large T antigen was found to be particularly impaired. These data emphasize the physiological importance of the latter phosphorylation site.
D000956:Antigens, Viral / Q000032:analysis*; D000957:Antigens, Viral, Tumor; D006207:Half-Life; D009154:Mutation; D010766:Phosphorylation; D010768:Phosphoserine / Q000378:metabolism*; D010769:Phosphothreonine / Q000378:metabolism*; D012694:Serine / Q000031:analogs & derivatives*; D013539:Simian virus 40 / Q000235:genetics / Q000276:immunology* / Q000378:metabolism; D013696:Temperature; D013912:Threonine / Q000031:analogs & derivatives*
D000956:Antigens, Viral; D000957:Antigens, Viral, Tumor; D010769:Phosphothreonine; D010768:Phosphoserine; D013912:Threonine; D012694:Serine