The integrin beta 1 subunit associates with the vitronectin receptor alpha v subunit to form a novel vitronectin receptor in a human embryonic kidney cell line.
We describe a novel integrin heterodimer on the surface of the human embryonic kidney cell line 293. This receptor is comprised of alpha v and beta 1 subunits, each of which has been previously found in association with other integrin subunits. This alpha v.beta 1 complex was identified as the predominant vitronectin receptor (VnR) on the surface of 293 cells by immunoprecipitation with antibodies raised against the alpha v subunit. Polymerase chain reaction analysis detected mRNAs for alpha v and beta 1 subunits while no evidence was obtained for beta 2, beta 3, or alpha IIb integrin subunit mRNA. Immunoprecipitation of surface-iodinated proteins with antibodies to alpha v gave bands of 150 and 120 kDa. The 120-kDa band reacted with antibodies to beta 1 in immunoblotting experiments. 293 cells adhere to vitronectin, fibronectin, laminin, and collagen IV, while von Willebrand factor and fibrinogen, known ligands of the VnR (alpha v.beta 3), did not support adhesion. A polyclonal antibody directed against both subunits of the VnR (alpha v, beta 3) inhibits attachment of 293 cells to vitronectin but not to other adhesive proteins. A beta 1-specific monoclonal inhibited attachment to fibronectin, laminin, and collagen IV, known ligands of beta 1 integrins, as well as vitronectin. This novel (alpha v. beta 1) VnR thus appears to mediate cell adhesion exclusively to vitronectin, in contrast to previously described VnRs which have multiple ligands.
Bodary
S C
SC
Department of Biomolecular Chemistry, Genentech, Inc., South San Francisco, California 94080.
McLean
J W
JW
D000906:Antibodies; D000936:Antigen-Antibody Complex; D002448:Cell Adhesion; D002460:Cell Line; D004622:Embryo, Mammalian; D005109:Extracellular Matrix / Q000276:immunology; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D016023:Integrins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D007668:Kidney; D046911:Macromolecular Substances; D008970:Molecular Weight; D016133:Polymerase Chain Reaction; D012333:RNA, Messenger; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic / Q000378:metabolism*; D019030:Receptors, Vitronectin
D000906:Antibodies; D000936:Antigen-Antibody Complex; D005353:Fibronectins; D016023:Integrins; D046911:Macromolecular Substances; D012333:RNA, Messenger; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic; D019030:Receptors, Vitronectin