Alternative proteolytic processing of platelet membrane glycoprotein IIb

J. C. Loftus, E. F. Plow, L. K. Jennings, M. H. Ginsberg

Research output: Contribution to journalArticle

33 Scopus citations

Abstract

Platelet membrane glycoprotein (GP) IIb-IIIa is a component of a receptor for the adhesive proteins fibrinogen, fibronectin, and von Willebrand factor. GPIIb is initially synthesized as a single-chain polypeptide that is proteolytically processed to yield the two chains of mature GPIIb present on the cell surface. Analysis of the amino acid sequence surrounding the proposed light-heavy chain junction of GPIIb suggests a second potential site following a pair of basic residues 12-15 residues upstream from the reported amino terminus of the light chain. We have utilized anti-peptide antibodies to examine the possibility of alternative cleavage at these two potential sites. Peptide V43 precedes the dibasic sequence and is known to reside in the heavy chain. Peptide V41 contains the sequence between the two potential sites. In immunoblots, anti-V43 reacted only with the heavy chain while anti-V41 reacted only with the light chain. Immunoprecipitation of surface-labeled platelets indicated 97% of the GPIIb light chain contains the V41 sequence while approximately 3% of GPIIb molecules lack the V41 sequence on both the light and heavy chains. These data indicate that GPIIb is primarily cleaved 12-15 amino acids upstream from the reported amino terminus of the light chain while in a minor proportion of GPIIb molecules cleavage occurs at both sites.

Original languageEnglish (US)
Pages (from-to)11025-11028
Number of pages4
JournalJournal of Biological Chemistry
Volume263
Issue number23
StatePublished - Jan 1 1988

    Fingerprint

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Loftus, J. C., Plow, E. F., Jennings, L. K., & Ginsberg, M. H. (1988). Alternative proteolytic processing of platelet membrane glycoprotein IIb. Journal of Biological Chemistry, 263(23), 11025-11028.