Proteins specified by herpesvirus saimiri: identification and properties of virus-specific polypeptides in productively infected cells

The synthesis and accumulation of more than 30 virus-induced polypeptides was detected after infection of permissive primate cells with high multiplicities of herpesvirus saimiri. These virus-induced polypeptides had apparent mol. wt. of from 12,000 (12K) to 250K and differed in molar abundance by up to two orders of magnitude. The majority of virus-induced polypeptides satisfied multiple criteria for their virus specificity. Polypeptides of 110K, 76K, 51K and 31K to 29K were synthesized at maximum rates early in infection, but the majority of proteins were made at high rates late in infection. Virus-specific polypeptides were substrates for a number of post-synthetic modifications. The 117K, 85K, 76K, 31K and 30K polypeptides were each processed to forms with altered electrophoretic mobility. The 117K and 85K polypeptides were among the virus-specified substrates for glycosylation and virus-induced polypeptides of 59K, 51K, 30K and 26K were phosphorylated. The early 51K phosphoprotein and the 30K to 31K polypeptides were rapidly translocated to the nucleus of infected cells. The 31K polypeptide was processed to a 29K product which remained stably associated with the nuclear fraction. The 30K nuclear protein was shown to be the precursor of a 28K polypeptide which was released in a soluble form into the cytoplasmic fraction and the culture medium of cells at late times in the virus growth cycle. Many other polypeptides accumulated slowly in nuclear (e.g. 250K, 150K, 130K, 110K and 38K) or in cytoplasmic (e.g. 117K, 85K and 28K) fractions of infected cells in forms which could be differentiated by the use of detergents or differences in stability to salt extraction. The mol. wt., relative molarities and some features of the post-synthetic processing of herpesvirus saimiri polypeptides more closely resembled the properties of gene products of Epstein-Barr virus than those of herpes simplex virus.