title: Amino acid sequence of the human fibronectin receptor.
abstract: The amino acid sequence deduced from cDNA of the human placental fibronectin receptor is reported. The receptor is composed of two subunits: an alpha subunit of 1,008 amino acids which is processed into two polypeptides disulfide bonded to one another, and a beta subunit of 778 amino acids. Each subunit has near its COOH terminus a hydrophobic segment. This and other sequence features suggest a structure for the receptor in which the hydrophobic segments serve as transmembrane domains anchoring each subunit to the membrane and dividing each into a large ectodomain and a short cytoplasmic domain. The alpha subunit ectodomain has five sequence elements homologous to consensus Ca2+-binding sites of several calcium-binding proteins, and the beta subunit contains a fourfold repeat strikingly rich in cysteine. The alpha subunit sequence is 46% homologous to the alpha subunit of the vitronectin receptor. The beta subunit is 44% homologous to the human platelet adhesion receptor subunit IIIa and 47% homologous to a leukocyte adhesion receptor beta subunit. The high degree of homology (85%) of the beta subunit with one of the polypeptides of a chicken adhesion receptor complex referred to as integrin complex strongly suggests that the latter polypeptide is the chicken homologue of the fibronectin receptor beta subunit. These receptor subunit homologies define a superfamily of adhesion receptors. The availability of the entire protein sequence for the fibronectin receptor will facilitate studies on the functions of these receptors.
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D004247:DNA / Q000302:isolation & purification; D005260:Female; D006801:Humans; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009693:Nucleic Acid Hybridization; D010920:Placenta / Q000276:immunology; D012333:RNA, Messenger / Q000235:genetics; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic / Q000235:genetics*
chemical_list: D046911:Macromolecular Substances; D012333:RNA, Messenger; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic; D004247:DNA