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Characterization of a membrane‐associated glycoprotein complex implicated in cell adhesion to fibronectin
Author(s) -
Hasegawa Takayuki,
Hasegawa Etsuko,
Chen WenTien,
Yamada Kenneth M.
Publication year - 1985
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.240280409
Subject(s) - glycoprotein , fibronectin , biochemistry , isoelectric point , isoelectric focusing , protein subunit , monoclonal antibody , chemistry , band 3 , affinity chromatography , extracellular matrix , neuraminidase , microbiology and biotechnology , biology , antibody , membrane protein , membrane , enzyme , immunology , gene
We have characterized a 140‐kDa glycoprotein complex purified by a monoclonal antibody and implicated in cell adhesion to the extracellular molecule fibronectin. Three major polypeptide components were purified by monoclonal antibody JG22E, which had apparent molecular weights of 155,000 (band 1), 135,000 (band 2), and 120,000 (band 3). In two‐dimensional gel electrophoresis, each subunit migrated as either a broad band or a series of spots at acidic isoelectric points. After treatment with neuraminidase, the spots became focused around pH 6.2 (band 1), pH 5.6 (band 2), and pH 5.3 (band 3). These three major bands were compared by two‐dimensional peptide mapping in a series of pairwise combinations and were found to be distinct proteins. In sucrose gradients, these proteins co‐migrated as a complex sedimenting at approximately 8.4 S either before or after affinity purification, whereas separated subunits migrated at 4.7 to 5.8 S. Amino acid analysis revealed no detectable hydroxyproline and a composition characterized by a substantial number of cysteine residues compared to the average protein. Our results suggest that a noncovalent complex of structurally distinct glycoproteins is involved in adhesive interactions of fibronectin with cells.