Building of the Tetraspanin Web: Distinct Structural Domains of CD81 Function in Different Cellular Compartments

作者：Tsipi Shoham, Ranjani Rajapaksa, Chiung-Chi Kuo, Joseph Haimovich, Shoshana Levy · 发表于：Molecular and Cellular Biology · 年份：2006 · DOI：10.1128/mcb.26.4.1373-1385.2006 · 被引用次数：96 · 研究领域：Cell Adhesion Molecules Research、Platelet Disorders and Treatments、Immune Cell Function and Interaction

The tetraspanin web is composed of a network of tetraspanins and their partner proteins that facilitate cellular interactions and fusion events by an unknown mechanism. Our aim was to unravel the web partnership between the tetraspanin CD81 and CD19, a cell surface signaling molecule in B lymphocytes. We found that CD81 plays multiple roles in the processing, intracellular trafficking, and membrane functions of CD19. Surprisingly, these different roles are embodied in distinct CD81 domains, which function in the different cellular compartments: the N-terminal tail of CD81 has an effect on the glycosylation of CD19; the first transmembrane domain of CD81 is sufficient to support the exit of CD19 from the endoplasmic reticulum, although the large extracellular loop (LEL) of CD81 associates physically with CD19 early during biosynthesis; and finally, the TM2 and TM3 domains of CD81 play a role in the transmission of signals initiated upon engagement of the LEL. The participation of distinct CD81 domains in varied functions may explain the pleiotropic effects of CD81 within the tetraspanin web.