Calcium-dependent properties of CIB binding to the integrin αIIb cytoplasmic domain and translocation to the platelet cytoskeleton

David D. Shock, Ulhas P. Naik, Julia Elizabeth Brittain, Suresh K. Alahari, John Sondek, Leslie V. Parise

Research output: Contribution to journalArticle

63 Citations (Scopus)

Abstract

The αIIbβ3 integrin receives signals in agonist-activated platelets, resulting in its conversion to an active conformation that binds fibrinogen, thereby mediating platelet aggregation. Fibrinogen binding to αIIbβ3 subsequently induces a cascade of intracellular signalling events. The molecular mechanisms of this bi-directional aIIbβ3-mediated signalling are unknown but may involve the binding of proteins to the integrin cytoplasmic domains. We reported previously the sequence of a novel 22-kDa, EF-hand-containing, protein termed CIB (calcium- and integrin-binding protein) that interacts specifically with the αlIb cytoplasmic domain in the yeast two-hybrid system. Further analysis of numerous tissues and cell lines indicated that CIB mRNA and protein are widely expressed. In addition, isothermal titration calorimetry indicated that CIB binds to an αIIb cytoplasmic-domain peptide in a Ca2+-dependent manner, with moderate affinity (K(d) 700 nM) and 1:1 stoichiometry. In aggregated platelets, endogenous CIB and αIIbβ3 translocate to the Triton X-100-insoluble cytoskeleton in a parallel manner, demonstrating that the cellular localization of CIB is regulated, potentially by αIIbβ3. Thus CIB may contribute to integrin-related functions by mechanisms involving Ca2+-modulated binding to the αIIb cytoplasmic domain and changes in intracellular distribution.

Original languageEnglish (US)
Pages (from-to)729-735
Number of pages7
JournalBiochemical Journal
Volume342
Issue number3
DOIs
StatePublished - Sep 15 1999

Fingerprint

Calcium-Binding Proteins
Platelets
Cytoskeleton
Protein Binding
Integrins
Carrier Proteins
Blood Platelets
Calcium
Fibrinogen
EF Hand Motifs
Calorimetry
Two-Hybrid System Techniques
Octoxynol
Hybrid systems
Titration
Platelet Aggregation
Stoichiometry
Yeast
Conformations
Proteins

Keywords

  • EF-hand motif
  • Fibrinogen
  • Intracellular signalling
  • Platelet activation
  • Platelet aggregation

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

Cite this

Calcium-dependent properties of CIB binding to the integrin αIIb cytoplasmic domain and translocation to the platelet cytoskeleton. / Shock, David D.; Naik, Ulhas P.; Brittain, Julia Elizabeth; Alahari, Suresh K.; Sondek, John; Parise, Leslie V.

In: Biochemical Journal, Vol. 342, No. 3, 15.09.1999, p. 729-735.

Research output: Contribution to journalArticle

Shock, David D. ; Naik, Ulhas P. ; Brittain, Julia Elizabeth ; Alahari, Suresh K. ; Sondek, John ; Parise, Leslie V. / Calcium-dependent properties of CIB binding to the integrin αIIb cytoplasmic domain and translocation to the platelet cytoskeleton. In: Biochemical Journal. 1999 ; Vol. 342, No. 3. pp. 729-735.
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