Author: Nat Pernick, M.D. (see Authors page)

Revised: 24 November 2015, last major update June 2005

Copyright: (c) 2002-2015,, Inc.

PubMed Search: Integrins [title]

Table of Contents
Definition / General | See also
Definition / General
  • Family of adhesion proteins with various functions, including major cell surface receptors for extracellular matrix proteins
  • Membrane glycoprotein heterodimer complexes that are assembled by noncovalent association of alpha and beta subunits, with active and inactive states; currently are 18 alpha subunits and 8 beta subunits, which combine to form 24 different integrins
  • Alpha subunit has extracellular domain that binds matrix molecules; beta subunit has cytoplasmic domain that interacts with actin cytoskeleton, microfilament-associated proteins and signaling mediators
  • Functions:
    • Homing of progenitor T cells to thymus
    • Differentiation and proliferation of B and T cells in bone marrow, transcription of genes involved in cell-cell contacts and endothelial cell migration
  • Activated by intracellular bacteria and by extracellular ligand binding
  • Inhibited by RGD (arginine-glycine-aspartic acid) sequence, which blocks integrins from binding to ligands
See also
    Integrin alpha 2b beta 3
    • General:
      • Also called glycoprotein IIa / IIIb, fibrinogen receptor
      • Platelet integrin that induces platelet aggregation
      • Antibodies to alpha2b beta3 prevent ischemia of percutaneous coronary angioplasty

    Integrin alpha 3 beta 2
    • General:
      • Fibrinogen forms cross links with this platelet receptor during platelet aggregation

    Integrin alpha 4 beta 1

    Integrin alpha 5 beta 1
    • General:
      • Also called CD29, fibronectin receptor
      • Supports assembly of fibronectin matrix

    Integrin alpha 4 beta 1
    • General:
      • Have role in tumor cell migration and invasion in vitro
      • Reduced expression in invasive bladder CA
      • Principal ligand is laminin-5 protein (component of epithelial basement membrane)
      • Protein production is characteristic of basal / myoepithelial type of breast carcinoma
      • Beta4 subunit is only expressed in combination with alpha 6 subunit
    • Micro images:

      Missing Image

      Breast carcinoma

    • Additional references:

    Integrin alpha v beta 3
    • General:
      • Specifically expressed in endothelial cells of newly formed blood vessels
      • May play a role in central nervous system neoplasms
    • Positive staining - disease:

    Integrin beta 2