Processing of the p62 envelope precursor protein of Semliki Forest virus.

摘要: The spike protein of Semliki Forest virus is composed three subunits, E1, E2, and E3, which mediate the fusion membrane with that host cell. E2 E3 are synthesized as a precursor, p62, cleaved post-translationally after an Arg-His-Arg-Arg sequence. In vitro mutagenesis cDNA clone proteins was used to specifically alter amino acids in this cleavage site. Cleavage p62 completely blocked by mutation proximal Arg residue Phe, without affecting transport or surface expression protein. resulted loss activity within physiological pH range. Fusion restored exogenous chymotrypsin showed same low dependence wild type. sensitivity newly investigated pulse-chase analysis treatment detergent solution. sensitive immediately following its synthesis. Protein trapped rough endoplasmic reticulum Golgi apparatus carbonyl cyanide m-chlorophenylhydrazone, monensin, Brefeldin A also fully cleavage. These results suggest does not require organelle-mediated conformational change for processing. Thus, vivo, site processing probably controlled location enzyme, rather than substrate.