Immunochemical and amino-terminal sequence comparison of two cytoadhesins indicates they contain similar or identical β subunits and distinct α subunits

M. H. Ginsberg, J. Loftus, J. J. Ryckwaert, M. Pierschbacher, R. Pytela, E. Ruoslahti, E. F. Plow

Research output: Contribution to journalArticle

54 Scopus citations

Abstract

Platelet membrane glycoprotein (GP) IIb-IIIa is functionally and antigenically related to proteins present on many cell types, suggesting that it is a member of the proposed cytoadhesin family of membrane proteins. We have compared the purified tissue vitronectin receptor (VnR) with GP IIb-IIIa. Anti-VnR immunoprecipitated GP IIb-IIIa and a related endothelial cell protein. In immunoblots, GP IIIa reacted with anti-VnR and the β subunit of the VnR reacted with poly and monoclonal anti-GP IIIa. In contrast, the α subunit of the VnR failed to react either with a polyclonal anti-GP IIb or with monoclonal anti-GP IIb. Furthermore, the amino-terminal sequence of GP IIIa and the β subunit of VnR were identical at determined residues while the α subunit and the GP IIb were different, but showed 33% identity. These data indicate the identity or close homology of GP IIIa and the β subunit of the VnR. In contrast, the α subunit and GP IIb are distinct polypeptides which may be homologous. Since GP IIb-IIIa and the VnR differ in ligand recognition specificity, the data also suggest that this specificity may be governed by the α subunit of cytoadhesins.

Original languageEnglish (US)
Pages (from-to)5437-5440
Number of pages4
JournalJournal of Biological Chemistry
Volume262
Issue number12
StatePublished - Sep 15 1987

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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