Purification and functional characterization of integrin alpha v beta 5. An adhesion receptor for vitronectin.
We have purified a novel member of the integrin gene family from placenta that serves as a vitronectin receptor. This integrin is composed of the alpha v subunit and a beta subunit that we designate beta 5. Purification was accomplished by immunodepleting a placental extract of integrin alpha v beta 3, allowing us to purify alpha v beta 5 from the remaining extract by monoclonal antibody affinity chromatography on LM 142-Sepharose, which binds to the alpha v subunit. Purification to homogeneity was subsequently achieved by affinity chromatography on wheat germ lectin-Sepharose. Western blot analysis with antibodies raised against alpha v beta 5 and alpha v beta 3 demonstrated that beta 3 and beta 5 were distinct but confirmed that the alpha subunit of the two integrins were immunologically identical. Similarly, antibodies that bind beta 3 proximal to the ligand-binding site failed to react with beta 5, indicating an architectural difference at the ligand-binding site of these related integrins. This structural difference apparently results in a functional distinction, since purified alpha v beta 3 bound to vitronectin, fibrinogen, von Willebrand factor, and fibronectin, whereas integrin alpha v beta 5 bound preferentially to vitronectin. Finally, we demonstrate by three criteria that beta 5 and beta x, the latter of which was identified in lung carcinoma cells (Cheresh, D. A., Smith, J. W., Cooper, H. M., and Quaranta, V. (1989) Cell 57, 59-69), are identical. First, peptide maps of beta x and beta 5 are identical. Secondly, polyclonal antibodies raised against alpha v beta 5 immunoprecipitate both beta 5 and beta x, and finally, the amino-terminal amino acid sequences of beta x and beta 5 are identical.
Smith
J W
JW
Department of Immunology (IMM13), Research Institute of Scripps Clinic, La Jolla, California 92037.
Vestal
D J
DJ
Irwin
S V
SV
Burke
T A
TA
Cheresh
D A
DA
D000595:Amino Acid Sequence; D000911:Antibodies, Monoclonal; D015153:Blotting, Western; D002845:Chromatography; D002846:Chromatography, Affinity; D005260:Female; D006023:Glycoproteins / Q000378:metabolism*; D006801:Humans; D007163:Immunosorbent Techniques; D016023:Integrins / Q000302:isolation & purification* / Q000378:metabolism; D008969:Molecular Sequence Data; D010449:Peptide Mapping; D010920:Placenta / Q000032:analysis; D011247:Pregnancy; D011971:Receptors, Immunologic / Q000378:metabolism; D019030:Receptors, Vitronectin; D019096:Vitronectin
D000911:Antibodies, Monoclonal; D006023:Glycoproteins; D016023:Integrins; D011971:Receptors, Immunologic; D019030:Receptors, Vitronectin; D019096:Vitronectin; C064660:integrin alphaVbeta5