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Interaction of the integrin beta1 cytoplasmic domain with ICAP-1 protein

X A Zhang1, M E Hemler

  • 1Dana-Farber Cancer Institute and Department of Pathology, Harvard Medical School, Boston, Massachusetts 02115, USA.

The Journal of Biological Chemistry
|December 29, 1998
PubMed

Insights

Integrin-associated protein ICAP-1 specifically binds to integrin beta1 cytoplasmic tails, influencing cell migration. This protein is phosphorylated upon adhesion and plays a role in beta1 integrin-dependent cell movement.

Area of Science:

  • Cell biology
  • Molecular and cell biology
  • Biochemistry

Background:

  • Integrins are crucial cell surface receptors mediating cell adhesion and migration.
  • Specific interactions between integrin subunits and associated proteins regulate integrin function.
  • Understanding these interactions is key to deciphering cellular signaling pathways.

Purpose of the Study:

  • To identify and characterize proteins that associate with the integrin beta1 cytoplasmic tail.
  • To investigate the functional role of ICAP-1 in beta1 integrin-mediated cellular processes.
  • To elucidate the molecular mechanisms underlying ICAP-1 and beta1 integrin interaction.

Main Methods:

  • Yeast two-hybrid screening to identify binding partners.
  • Co-immunoprecipitation in human cells to confirm protein interactions.
  • Site-directed mutagenesis to map critical interaction domains.
  • Cell migration assays (chemotaxis) using transfected cell lines.
  • Western blotting to assess protein phosphorylation levels.

Main Results:

  • ICAP-1 (integrin cytoplasmic domain-associated protein 1) specifically binds to the integrin beta1 cytoplasmic tail, not other beta subunits.
  • The C-terminal 14 amino acids of the beta1 tail are essential for ICAP-1 binding.
  • ICAP-1 is ubiquitously expressed and exists in 27- and 31-kDa forms.
  • ICAP-1 phosphorylation is constitutive and increases upon cell spreading on fibronectin.
  • ICAP-1 transfection enhances beta1 integrin-dependent cell migration on fibronectin.

Conclusions:

  • ICAP-1 is a specific binding partner for integrin beta1.
  • ICAP-1 phosphorylation is regulated by beta1 integrin-mediated adhesion.
  • ICAP-1 plays a significant role in regulating beta1 integrin-dependent cell migration.

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