PC phosphorylation increases the ability of AFAP-110 to cross-link actin filaments

Mol Biol Cell. 2002 Jul;13(7):2311-22. doi: 10.1091/mbc.e01-12-0148.

Abstract

The actin filament-associated protein and Src-binding partner, AFAP-110, is an adaptor protein that links signaling molecules to actin filaments. AFAP-110 binds actin filaments directly and multimerizes through a leucine zipper motif. Cellular signals downstream of Src(527F) can regulate multimerization. Here, we determined recombinant AFAP-110 (rAFAP-110)-bound actin filaments cooperatively, through a lateral association. We demonstrate rAFAP-110 has the capability to cross-link actin filaments, and this ability is dependent on the integrity of the carboxy terminal actin binding domain. Deletion of the leucine zipper motif or PKC phosphorylation affected AFAP-110's conformation, which correlated with changes in multimerization and increased the capability of rAFAP-110 to cross-link actin filaments. AFAP-110 is both a substrate and binding partner of PKC. On PKC activation, stress filament organization is lost, motility structures form, and AFAP-110 colocalizes strongly with motility structures. Expression of a deletion mutant of AFAP-110 that is unable to bind PKC blocked the effect of PMA on actin filaments. We hypothesize that upon PKC activation, AFAP-110 can be cooperatively recruited to newly forming actin filaments, like those that exist in cell motility structures, and that PKC phosphorylation effects a conformational change that may enable AFAP-110 to promote actin filament cross-linking at the cell membrane.

Publication types

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

MeSH terms

  • Actinin / metabolism
  • Actins / metabolism*
  • Animals
  • Binding Sites
  • Cell Line
  • Cross-Linking Reagents / metabolism
  • Enzyme Activation
  • Leucine Zippers
  • Microfilament Proteins / genetics
  • Microfilament Proteins / metabolism*
  • Phosphoproteins / genetics
  • Phosphoproteins / metabolism*
  • Phosphorylation
  • Polymers / metabolism
  • Protein Binding
  • Protein Conformation
  • Protein Kinase C / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism

Substances

  • AFAP 110
  • Actins
  • Cross-Linking Reagents
  • Microfilament Proteins
  • Phosphoproteins
  • Polymers
  • Recombinant Fusion Proteins
  • Recombinant Proteins
  • Actinin
  • Protein Kinase C