Dissociation of patching by latent membrane protein-1 of Epstein-Barr virus from its stimulation of NF-kappaB activity.

Alterations were made in the amino terminus and the first two transmembrane-spanning regions of the latent membrane protein-1 (LMP-1) of Epstein-Barr virus. These mutant proteins were tested for their abilities to patch and to stimulate NF-kappaB activity. A subset of these derivatives retains the wild-type topology of LMP-1 in the plasma membrane, but has lost the ability to patch. Deletion of residues 9-20 of LMP-1, which contain potential SH3-binding motifs, abrogates patching of LMP-1. However, mutation of the prolines within these motifs, which eliminates binding of LMP-1 to SH3 domains in vitro, does not prevent patching by LMP-1. Deletion of the first two transmembrane regions of LMP-1 does prevent it patching. Some of the derivatives of LMP-1 which do not patch do stimulate NF-kappaB activity. Patching by LMP-1 appears to be a higher-order assemblage of protein that is compatible with the stimulation of NF-kappaB activity but is not necessary for this signalling.