摘要
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class="h3">Summary
Tetraspanins are commonly believed to act only as 鈥渕olecular facilitators,鈥?with no direct role in signal transduction. We herein demonstrate that upon ligation, CD37, a tetraspanin molecule expressed on mature normal and transformed B cells, becomes tyrosine phosphorylated, associates with proximal signaling molecules, and initiates a cascade of events leading to apoptosis. Moreover, we have identified two tyrosine residues with opposing regulatory functions: one lies in the N-terminal domain of CD37 in a predicted 鈥淚TIM-like鈥?motif and mediates SHP1-dependent death, whereas the second lies in a predicted 鈥淚TAM motif鈥?in the C-terminal domain of CD37 and counteracts death signals by mediating phosphatidylinositol 3-kinase-dependent survival.