The cytoplasmic domains of many membrane proteins contain sorting signals that mediate their endocytosis from the plasma membrane. VZV gB contains three consensus internalization motifs within its cytoplasmic domain: YMTL (aa 818-821), YSRV (aa 857-860), and LL (aa 841-842). To determine whether VZV gB is internalized from the plasma membrane, and whether these motifs are required for its endocytosis, we compared the internalization of native gB to that of gB containing mutations in each of the predicted internalization motifs. VZV gB present on the surface of transfected cells associated with clathrin and was efficiently internalized to the Golgi apparatus within 60 min at 37 degrees C. VZV gB containing the mutation Y857 failed to be internalized, while gB-Y818A was internalized but did not accumulate in the Golgi. These data indicate that the internalization of VZV gB, and its subsequent localization to the Golgi, is mediated by two tyrosine-based sequence motifs in its cytoplasmic domain.
Copyright 2001 Academic Press.