Submitted August 23, 2007
Accepted February 13, 2008
Identification of a major GpVI binding locus in human type III collagen
Gavin E Jarvis*, Nicolas Raynal, Jonathan P Langford, David J Onley, Allen Andrews, Peter A Smethurst, and Richard W Farndale
Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
Department of Haematology, University of Cambridge, Cambridge, United Kingdom
* Corresponding author; email: gej1000{at}cam.ac.uk.
We have analysed the adhesion of human and murine platelets, and of recombinant human and murine GpVI ectodomains, to synthetic triple-helical collagen-like peptides. These included 57 peptides derived from the sequence of human type III collagen and 9 peptides derived from the cyanogen bromide fragment of bovine type III collagen, 
1(III)CB4. We have identified several peptides which interact with GpVI, in particular a peptide designated III-30 with the sequence GAOGLRGGAGPOGPEGGKGAAGPOGPO. Both human and murine platelets bound to peptide III-30 in a GpVI-dependent manner. III-30 also supported binding of recombinant GpVI ectodomains. Cross-linked III-30 induced aggregation of human and murine platelets although with a lower potency than collagen-related peptide. Modifications of the peptide sequence indicated that the hydroxyproline residues play a significant role in supporting its GpVI reactivity. However, many peptides containing OGP/GPO motifs did not support adhesion to GpVI. These data indicate that the ability of a triple-helical peptide to bind GpVI is not solely determined by the presence or spatial arrangement of these OGP/GPO motifs within the peptides.
