Identification of the cytoskeletal protein alpha-actinin as a platelet thrombospondin-binding protein

FEBS Lett. 1995 May 8;364(2):109-14. doi: 10.1016/0014-5793(95)00362-d.

Abstract

Binding of the alpha-granular thrombospondin (TSP) to the plasma membrane of activated platelets has long been documented, yet the molecular mechanism involved in its secretion and surface expression have not been elucidated. Using a ligand blot binding assay where electrophoretically separated platelet proteins were incubated with purified 125I-labeled TSP, we observed a strong interaction of [125I]TSP with a 100 kDa single chain protein. On performing a platelet subfractionation, the 100 kDa protein was predominantly localized in the cytosol from which it was purified by preparative electrophoresis and was identified by amino acid sequencing to the cytoskeletal protein, alpha-actinin. We further demonstrated that [125I]TSP interacts with alpha-actinin in a specific manner and with a high affinity (Kd = 6.6 nM) in a solid-phase binding assay.

MeSH terms

  • Actinin / blood*
  • Actinin / chemistry
  • Actinin / isolation & purification
  • Blood Platelets / chemistry
  • Blood Platelets / metabolism*
  • Carrier Proteins / blood
  • Carrier Proteins / chemistry
  • Carrier Proteins / isolation & purification
  • Cell Membrane / metabolism
  • Humans
  • In Vitro Techniques
  • Membrane Glycoproteins / metabolism*
  • Molecular Weight
  • Platelet Activation / physiology
  • Subcellular Fractions / metabolism
  • Thrombospondins

Substances

  • Carrier Proteins
  • Membrane Glycoproteins
  • Thrombospondins
  • Actinin