Ba. Brody et al., POSTASSEMBLY CLEAVAGE OF A RETROVIRAL GLYCOPROTEIN CYTOPLASMIC DOMAINREMOVES A NECESSARY INCORPORATION SIGNAL AND ACTIVATES FUSION ACTIVITY, Journal of virology, 68(7), 1994, pp. 4620-4627
Viral protease-mediated cleavage within the cytoplasmic domain of the
transmembrane (TM) glycoprotein of the type D retrovirus, Mason-Pfizer
monkey virus, removes approximately 16 amino acids from the carboxy t
erminus of the protein. To determine the functional significance of th
is cleavage in the virus life cycle, we introduced premature stop codo
ns into the TM coding domain, resulting in the production of truncated
glycoproteins. Progressive truncation of the cytoplasmic domain ident
ified the carboxy-terminal third as being required for efficient incor
poration of the glycoprotein complex into budding virions and profound
ly increased the fusogenic capability of the TM glycoprotein. These re
sults, together with the ability of matrix protein mutations to suppre
ss TM cleavage, imply that this portion of the glycoprotein interacts
specifically with the capsid proteins during budding, suppressing glyc
oprotein fusion function until virus maturation has occurred.