期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2004
卷号：101
期号：12
页码：4094-4099
DOI：10.1073/pnas.0400742101
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Cytoplasmic face-mediated integrin inside-out activation remains a paradigm in transmembrane signal transduction. Emerging evidence suggests that this process involves dissociation of the complex between the integrin cytoplasmic tails; however, a dynamic image of how it occurs on the membrane surface remains elusive. We show here that, whereas membrane-proximal helices of integrin /{beta} cytoplasmic tails associate in cytoplasm-like aqueous medium, they become partially embedded into membranemimetic micelles when unclasped. Membrane embedding induces substantial structural changes of the cytoplasmic tails as compared to their aqueous conformations and suggests there may be an upward movement of the membrane-proximal helices into the membrane during their separation. We further demonstrate that the {beta}3 tail exhibits additional membrane binding site at its C terminus containing the NPLY motif. Talin, a key intracellular integrin activator, recognizes this site as well as the membrane-proximal helix, thereby promoting cytoplasmic tail separation along the membrane surface. These data provide a structural basis of membrane-mediated changes at the cytoplasmic face in regulating integrin activation and signaling.
