Fibulin (FY-beau-lin) is the prototypic member of a multigene family, currently with seven members. Fibulin-1 is a calcium-binding glycoprotein. In vertebrates, fibulin-1 is found in blood and extracellular matrices. In the extracellular matrix, fibulin-1 associates with basement membranes and elastic fibers. The association with these matrix structures is mediated by its ability to interact with numerous extracellular matrix constituents including fibronectin, proteoglycans, laminins and tropoelastin. In blood, fibulin-1 binds to fibrinogen and incorporates into clots.