Transport and secretion of truncated derivatives of herpes simplex virus 1 glycoprotein B.

Herpes simplex virus 1 (HSV-1) glycoprotein B (gB) is one of several glycoproteins that compose the virion envelope. In infected cells, gB is a transmembrane glycoprotein that dimerizes and is glycosylated during its transport through the exocytic pathway to the cell surface. To understand the structural requirements for the transport of gB, we analyzed the processing, dimerization, and transport of mutated forms lacking the transmembrane region and the carboxy terminus of the molecule. Our studies showed that conversion of the membrane-anchored form of gB into soluble forms of different lengths resulted in slowed transport rates and incomplete processing. The longer derivatives, gB-(1-690) and gB-(1-690 delta 849), formed dimers but were incompletely transported and were retained within cells. Similar results were obtained with gB-(1-600), which failed to form dimers. In contrast, gB-(1-475), which also failed to form dimers, was transported and secreted from cells. These findings indicate that dimerization is not required for the transport of short, soluble forms of gB through the exocytic pathway provided that conformational regions contained within these shortened molecules are properly assembled.