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.
Department of Biomolecular Chemistry, Genentech, Inc., South San Francisco, California 94080.
S C
SC
Bodary
J W
JW
McLean
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