Identification of putative ligand binding sites within I domain of integrin α2β1 (VLA-2,CD49b/CD29).

Vol. 269, p. 9659 In this paper, we discussed that the Arg-242 → Ala (R242A) mutation of α2 blocks the binding of monoclonal antibody 5E8. Recently, we found that there is another mutation, Tyr-216 → Ser, in the original R242A α2 construct that was used in the study. We developed two α2 cDNA constructs, one with a single R242A mutation and one with a single Tyr-216 → Ala (Y216A) mutation, and characterized them. We found that the Y216A mutation actually blocks binding of 5E8 to α2β1, but the R242A mutation does not. We conclude that the original blocking effect of the 5E8 binding is actually due to the Tyr-216 mutation, not the Arg-242 mutation. Neither mutation blocks binding of collagen to α2β1. “R242A” in the paper should be read “Y216A.”