Identification of integrin-like matrix receptors with affinity for interstitial collagens.
Antibodies to a rat liver membrane glycoprotein with an Mr of 115,000 (nonreduced) inhibited the attachment of rat hepatocytes and primary rat heart fibroblasts to both collagen and fibronectin. The Mr 115,000 glycoprotein cross-reacted immunologically with the beta 1-chain of the rat hepatocyte fibronectin receptor (HFNR), and the two proteins showed identical peptide maps after proteolytic cleavage. It was concluded that the Mr 115,000 protein was similar or identical to the beta 1-chain of Arg-Gly-Asp (RGD)-directed matrix receptors. Although collagen type I contains several RGD sequences, the attachment of hepatocytes and fibroblasts to collagen type I was not inhibited by the synthetic peptide GRGDTP in concentrations that blocked adhesion to fibronectin. Furthermore, hepatocytes adhered equally well to collagen fragments, generated by cyanogen bromide cleavage, lacking RGD sequences as to fragments containing this sequence. Antibodies to the Mr 115,000 protein inhibited the adhesion of hepatocytes to both types of collagen fragments. Taken together, these data indicate the presence of collagen receptors that share the beta-subunit with the HFNR but that are not directed to RGD sequences. Tentative alpha-chains of the collagen matrix receptor complex were isolated by immunoprecipitation of surface 125I-labeled fibroblast membrane proteins purified by affinity chromatography on immobilized collagen type I. Data are presented indicating that proteins with Mr around 145,000 and 170,000 (nonreduced) are associated in noncovalently linked complexes with the Mr 115,000 protein. These complexes have affinity for collagen and thus have properties expected for integrin-like collagen receptors.
Gullberg
D
D
Department of Medical and Physiological Chemistry, Uppsala University, Sweden.
Terracio
L
L
Borg
T K
TK
Rubin
K
K
D000595:Amino Acid Sequence; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002448:Cell Adhesion / Q000187:drug effects; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D003094:Collagen / Q000378:metabolism*; D003488:Cyanogen Bromide; D004591:Electrophoresis, Polyacrylamide Gel; D007106:Immune Sera; D016023:Integrins; D008099:Liver / Q000166:cytology / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000302:isolation & purification / Q000378:metabolism*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009842:Oligopeptides / Q000494:pharmacology; D010446:Peptide Fragments / Q000032:analysis; D010449:Peptide Mapping; D051381:Rats; D011956:Receptors, Cell Surface / Q000302:isolation & purification / Q000378:metabolism*; D038981:Receptors, Collagen
D002352:Carrier Proteins; D007106:Immune Sera; D016023:Integrins; D008562:Membrane Glycoproteins; D009842:Oligopeptides; D010446:Peptide Fragments; D011956:Receptors, Cell Surface; D038981:Receptors, Collagen; D003094:Collagen; D003488:Cyanogen Bromide