THE 2 MAJOR ENVELOPE PROTEINS OF EQUINE ARTERITIS VIRUS ASSOCIATE INTO DISULFIDE-LINKED HETERODIMERS

In a coimmunoprecipitation assay,vith monospecific antisera, the two m ajor envelope proteins G(L) and M of equine arteritis virus were found to occur in heteromeric complexes in virions and infected cells. Whil e the G(L) protein associated with M rapidly and efficiently, newly sy nthesized M protein was incorporated into complexes at a slower rate, which implies that it interacts with G(L) molecules synthesized earlie r. Analysis under nonreducing conditions revealed that the G(L)/M comp lexes consist of disulfide-linked heterodimeric structures. Pulse-chas e experiments showed that virtually all G(L) monomers ended up in hete rodimers, whereas a fraction of the M protein persisted as monomers. T he M protein also formed covalently linked homodimers, but only the he terodimers were incorporated into virus particles.