Identification of an IQGAP1/AKAP79 complex in beta-cells

J Cell Biochem. 2003 Sep 1;90(1):97-108. doi: 10.1002/jcb.10604.

Abstract

IQGAP1, is a recently discovered scaffold protein proposed to regulate membrane cytoskeleton events through protein-protein interactions with F-actin, E-cadherin, beta-catenin, and CLIP170. The binding of IQGAP1 to its partners is regulated by calcium/calmodulin (Ca(++)/CaM) and the small molecular weight guanine nucleotide triphosphatases (GTPases), Cdc42, and Rac1. Here we identify a novel IQGAP1 scaffolding function by isolating the cyclic AMP dependent kinase (PKA) with IQGAP1. IQGAP1 was co-purified with PKA using 5'-cyclic AMP (cAMP) affinity chromatography and PKA activity was co-immunoprecipitated with IQGAP1 using an anti-IQGAP1 antibody. The association of IQGAP1 with PKA was shown to occur through a direct interaction between A kinase anchoring protein 79 (AKAP79) and the carboxyl-terminal domain of IQGAP1. This suggests that cAMP/PKA may be coupled with Ca(++)/CaM and GTPases through an IQGAP1/AKAP79 complex.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • A Kinase Anchor Proteins
  • Adaptor Proteins, Signal Transducing*
  • Animals
  • Calcium / metabolism
  • Calmodulin / metabolism
  • Carrier Proteins / metabolism*
  • Cattle
  • Cell Membrane / metabolism
  • Cells, Cultured
  • Cyclic AMP / metabolism
  • Cyclic AMP-Dependent Protein Kinases / metabolism
  • Humans
  • Islets of Langerhans / cytology
  • Islets of Langerhans / metabolism*
  • Macromolecular Substances
  • Protein Binding
  • Protein Structure, Tertiary
  • Rats
  • Recombinant Proteins / metabolism
  • Signal Transduction / physiology*
  • cdc42 GTP-Binding Protein / metabolism
  • rac GTP-Binding Proteins / metabolism
  • ras GTPase-Activating Proteins*

Substances

  • A Kinase Anchor Proteins
  • AKAP5 protein, human
  • Adaptor Proteins, Signal Transducing
  • Akap5 protein, rat
  • Calmodulin
  • Carrier Proteins
  • IQ motif containing GTPase activating protein 1
  • Macromolecular Substances
  • Recombinant Proteins
  • ras GTPase-Activating Proteins
  • Cyclic AMP
  • Cyclic AMP-Dependent Protein Kinases
  • cdc42 GTP-Binding Protein
  • rac GTP-Binding Proteins
  • Calcium