Human Skeletal Muscle-Specific alpha-actinin-2 and -3 Isoforms Form Homodimers and Heterodimers in Vitro and in Vivo

Biochem Biophys Res Commun. 1998 Jul 9;248(1):134-9. doi: 10.1006/bbrc.1998.8920.


Alpha-actinins belong to a family of actin-binding and crosslinking proteins and are expressed in many different cell types. Multiple isoforms of alpha-actinin are found in humans and are encoded by at least four distinct genes. Human skeletal muscle contains two sarcomeric isoforms, alpha-actinin-2 and -3. Previous studies have shown that the alpha-actinins function as anti-parallel homodimers but the question of heterodimer formation between two different isoforms expressed in the same cell type has not been explored. To address this issue, we expressed both alpha-actinin-2 and -3 in vitro and were able to detect their interaction by both blot overlay and co-immunoprecipitation methods. We were also able to demonstrate the presence of heterodimers in vivo in human skeletal muscle and in COS-1 cells transiently transfected with both isoforms. Our results clearly demonstrate the potential for alpha-actinin isoforms to form heterodimers which might have unique functional characteristics.

Publication types

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

MeSH terms

  • Actinin / chemistry*
  • Actinin / genetics
  • Amino Acid Sequence
  • Animals
  • COS Cells
  • Dimerization
  • Humans
  • Immunoblotting
  • Molecular Sequence Data
  • Muscle, Skeletal / chemistry*
  • Precipitin Tests
  • Protein Conformation
  • Transfection


  • Actinin