Identification of the 32 kDa components of bovine lens EDTA-extractable protein as endonexins I and II

Biochem J. 1990 Mar 1;266(2):505-11. doi: 10.1042/bj2660505.

Abstract

EDTA-extractable protein (EEP) is a mixture of major lens membrane proteins with molecular masses ranging from 32 kDa to 40 kDa. These bind to the lens membrane in a Ca2(+)-dependent manner. In the present study we have identified and purified two distinct 32 kDa components of EEP (designated as EEP 32-1 and EEP 32-2) from bovine lens that inhibit phospholipase A2 activity. Both EEP 32-1 and EEP 32-2 bind to phospholipid-containing liposomes and actin filaments in a Ca2(+)-dependent fashion. Immunochemical studies and two-dimensional electrophoreses demonstrate that the two proteins are distinct from one another. Both EEP 32-1 and EEP 32-2 are clearly different from calpactin (lipocortin) or its proteolytic fragments because they did not react with anti-[human placenta calpactin (lipocortin)] antibody. Our results also indicate that EEP 32-1 is very similar to endonexin I and that EEP 32-2 corresponds to endonexin II.

MeSH terms

  • Actins / metabolism
  • Amino Acid Sequence
  • Animals
  • Annexin A5
  • Calcium-Binding Proteins / immunology
  • Calcium-Binding Proteins / isolation & purification*
  • Cattle
  • Chromatography, Gel
  • Cross Reactions
  • Edetic Acid
  • Electrophoresis, Gel, Two-Dimensional
  • Lens, Crystalline / analysis*
  • Molecular Sequence Data
  • Molecular Weight
  • Phospholipases A / antagonists & inhibitors
  • Phospholipases A2
  • Phospholipids / metabolism

Substances

  • Actins
  • Annexin A5
  • Calcium-Binding Proteins
  • Phospholipids
  • Edetic Acid
  • Phospholipases A
  • Phospholipases A2