C-terminal domain of the Epstein-Barr virus LMP2A membrane protein contains a clustering signal

The latency-regulated transmembrane protein LMP2A interferes with signaling from the B-cell antigen receptor by recruiting the tyrosine kinases Lyn an d Syk and by targeting them for degradation by binding the cellular E3 ubiq uitin ligase AIP4. It has been hypothesized that this constitutive activity of LMP2A requires clustering in the membrane, but molecular evidence for t his has been lacking. In the present study we show that LMP2A coclusters wi th chimeric rat CD2 transmembrane molecules carrying the 27-amino-acid (aa) intracellular C terminus of LMP2A and that this C-terminal domain fused to the glutathione-S-transferase protein associates with LMP2A in cell lysate s. This molecular association requires neither the cysteine-rich region bet ween aa 471 and 480 nor the terminal three aa 495 to 497. We also show that the juxtamembrane cysteine repeats in the LMP2A C terminus are the major t argets for palmitoylation but that this acylation is not required for targe ting of LMP2A to detergent-insoluble glycolipid-enriched membrane microdoma ins.