The Journal of biological chemistry
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Mac-1 (CD11b/CD18), a leukocyte-restricted integrin receptor, mediates neutrophil/monocyte adhesion to vascular endothelium and phagocytosis of complement-opsonized particles. Recent studies have shown that Mac-1 also functions as a receptor for fibrinogen in a reaction linked to fibrin deposition on the monocyte surface. ⋯ Direct microsequence analysis and an epitope-mapped monoclonal antibody showed that D30 lacks the COOH-terminal dodecapeptide of the gamma chain as well as the Arg-Gly-Asp sequences in the A alpha chain. We conclude that fibrinogen interacts with the leukocyte integrin Mac-1 through a novel recognition site that is not shared with other known integrins that function as fibrinogen receptors.