Platelet integrin GPIIb/IIIa: structure-function correlations. An update and lessons from other integrins.

Glycoprotein (GP) IIb/IIIa complex (integrin alphaIIbbeta3) is the most abundant platelet receptor. It serves as an inducible receptor for adhesive proteins and is the best-studied member of the integrin family. Its major global structural features have been elucidated mainly during the last decade. Since 1995, there has been a substantial increase in structural information on adhesion molecule domains. The crystal structures of isolated integrin I domains have been solved. Although a high resolution picture of a whole integrin molecule is not yet available, the crystal structures together with biochemical, mutagenesis and modeling data provide a useful framework for interpreting current experimental evidence on structure-function correlations of integrin molecules and for guiding further experiment. The aim of this minireview is to update a previous one summarizing recent (1995-98) functional and structural data of GPIIb/IIIa and other integrins in the perspective of an emerging model of the structure, and bidirectional signaling mechanism through, integrin alphaIIbbeta3.