Cell surface-associated protein implicated in virulence by promoting bacterial attachment to both alpha- and beta-chains of human fibrinogen and inducing the formation of bacterial clumps. Partly responsible for mediating bacterial attachment to the highly keratinized squamous epithelial cells from the nasal cavity via an interaction with cytokeratin K10 (K10). Also promotes bacterial attachment to cultured keratinocytes, possibly through an interaction with cytokeratin K10. Binds mouse cytokeratin K10. Activates human platelet aggregation. Found in a ring-like distribution on the cell surface (PubMed:18800056). Colocalizes with SdrD (PubMed:18800056). Anchored to the cell wall by sortase A (Probable). The Asp/Ser-rich domain functions as a stalk to allow the ligand binding domain to be displayed in a functional form on the cell surface. Proteolytically cleaved by aureolysin (aur). This cleavage leads to the inactivation of ClfB. Belongs to the serine-aspartate repeat-containing protein (SDr) family.