Integrin Activation State Determines Selectivity for Novel Recognition Sites in Fibrillar Collagens

• Published in: The Journal of biological chemistry Vol. 279; no. 46; pp. 47763 - 47772
• Main Authors: Siljander, Pia R-M, Hamaia, Samir, Peachey, Anthony R, Slatter, David A, Smethurst, Peter A, Ouwehand, Willem H, Knight, C Graham, Farndale, Richard W
• Format: Journal Article
• Language: English
• Published: United States American Society for Biochemistry and Molecular Biology 12.11.2004
• Subjects: Amino Acid Motifs; Animals; Blood Platelets - metabolism; Cell Line; Collagen Type I - chemistry; Collagen Type I - genetics; Collagen Type I - metabolism; Humans; Integrin alpha Chains - genetics; Integrin alpha Chains - metabolism; Integrin alpha2beta1 - genetics; Integrin alpha2beta1 - metabolism; Peptides - chemistry; Peptides - genetics; Peptides - metabolism; Platelet Adhesiveness - physiology; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Recombinant Fusion Proteins - genetics; Recombinant Fusion Proteins - metabolism; Sequence Alignment
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M404685200

Only three recognition motifs, GFOGER, GLOGER, and GASGER, all present in type I collagen, have been identified to date for collagen-binding integrins, such as α 2 β 1 . Sequence alignment was used to investigate the occurrence of related motifs in other human fibrillar collagens, and located a conserved array of novel GER motifs within their triple helical domains. We compared the integrin binding properties of synthetic triple helical peptides containing examples of such sequences (GLSGER, GMOGER, GAOGER, and GQRGER) or the previously identified motifs. Recombinant inserted (I) domains of integrin subunits α 1 , α 2 and α 11 all bound poorly to all motifs other than GFOGER and GLOGER. Similarly, α 2 β 1 -containing resting platelets adhered well only to GFOGER and GLOGER, while ADP-activated platelets, HT1080 cells and two active α 2 I domain mutants (E318W, locked open) bound all motifs well, indicating that affinity modulation determines the sequence selectivity of integrins. GxO/SGER peptides inhibited platelet adhesion to collagen monomers with order of potency F ≥ L ≥ M > A. These results establish GFOGER as a high affinity sequence, which can interact with the α 2 I domain in the absence of activation and suggest that integrin reactivity of collagens may be predicted from their GER content.