tailieunhanh - Báo cáo khoa học: Mapping the binding domains of the aIIb subunit A study performed on the activated form of the platelet integrin aIIbb3

aIIbb3, a member of the integrin family of adhesive protein receptors, is the most abundant glycoprotein on platelet plasma-membranes and binds to adhesive proteins via the recognition of short amino acid sequences, for example the ubiquitous RGD , elucidation of the ligand-binding domains of the receptor remains controversial, mainly owing to the fact that integrins are conformationally labile during purification and storage. | Eur. J. Biochem. 270 3760-3767 2003 FEBS 2003 doi Mapping the binding domains of the aIIb subunit A study performed on the activated form of the platelet integrin aIIbp3 Nikolaos Biris1 Morfis Abatzis1 John V. Mitsios1 Maria Sakarellos-Daitsiotis1 Constantinos Sakarellos1 Demokritos Tsoukatos1 Alexandros D. Tselepis1 Lambros Michalis2 Dimitrios Sideris2 Georgia Konidou3 Ketty Soteriadou3 and Vassilios Tsikaris1 1 Department of Chemistry and 2Medical School University of loannina loannina Greece and 3Department of Biochemistry Hellenic Pasteur Institute Athens Greece aIIbb3 a member of the integrin family of adhesive protein receptors is the most abundant glycoprotein on platelet plasma-membranes and binds to adhesive proteins via the recognition of short amino acid sequences for example the ubiquitous RGD motif. However elucidation of the 1 g rmcl -binding domains of the receptor remains controversial mainly owing to the fact that integrins are conformationally labile during purification and storage. In tins uddy a detailed mapping of the extracellular region of the aIIb subunit is presented using overlapping 20-peptides in order to identify the binding sites of aIIb potentially involved in the platelet-aggregation event. Regíons aIIb 313-332 aIIb 265284 and aIIb 57-64 of aIIbb3 were identified as putative fibrinogen-binding domains because the corresponding peptides inhibited platelet aggregation and antagonized fibrinogen association possibly by interacting with this ligand. The tatter ÍS further urpported by the íìndíng that the above peptides did not interfere with the binding of PAC-1 to the activated form of aIIbb3. Furthtrmore. aIIb 313-332 was found to bind to fibrinogen in a solid-phase binding assay. It shoudd be emphatieed that all the exptrimnnis m this study were carried out on activated platelets and consequently on the activated form of this integrin receptor. We hypothesize that RAD and RAE adhesive motifs .