Ezrin-calpain I interactions in gastric parietal cells

Am J Physiol. 1993 Jul;265(1 Pt 1):C36-46. doi: 10.1152/ajpcell.1993.265.1.C36.


Gastric ezrin, a membrane-cytoskeletal linker with sequence homology to talin and erythrocyte band 4.1, has been associated with the remodeling of parietal cell apical membrane that occurs with adenosine 3',5'-cyclic monophosphate (cAMP)-dependent protein kinase stimulation. Here we examine the interrelationship between parietal cell ezrin and Ca(2+)-dependent protease activity. Addition of Ca2+ to sonicated gastric gland preparations rendered a relatively selective proteolysis of the 80-kDa ezrin, accompanied by the appearance of a 55-kDa breakdown product. Ca(2+)-dependent proteolysis of ezrin was blocked by E64, a cysteine protease inhibitor, or calpastatin, indicating calpain as the responsible protease. Degradation of ezrin in intact gastric glands was achieved by varying extracellular [Ca2+] and [ionomycin]. Ezrin degradation in situ was rapid and relatively selective, although Ca(2+)-dependent degradation of some spectrin-like bands was also observed. The effect of activated calpain I on parietal cell function was assessed by probing the secretory response to histamine stimulation using [14C]aminopyrine uptake, along with parallel measurements of calpain activity, over a wide range of ionomycin. Activation of calpain, as evidenced by loss of parietal cell ezrin, was correlated with decreased AP uptake by stimulated gastric glands, supporting a role for ezrin in the oxyntic secretory process. The calpain-ezrin interaction established here, and the similarities of calpain with talin and erythrocyte band 4.1, suggest a common feature to this family of ezrin/band 4.1/talin proteins that have been implicated in membrane-cytoskeletal association.

Publication types

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

MeSH terms

  • Animals
  • Calcium / metabolism
  • Calpain / isolation & purification
  • Calpain / metabolism*
  • Cytoskeletal Proteins
  • Endopeptidases / metabolism
  • In Vitro Techniques
  • Osmolar Concentration
  • Parietal Cells, Gastric / metabolism*
  • Peptide Hydrolases / metabolism
  • Phosphoproteins / metabolism*
  • Protons
  • Rabbits
  • Sonication
  • Subcellular Fractions / metabolism


  • Cytoskeletal Proteins
  • Phosphoproteins
  • Protons
  • ezrin
  • Endopeptidases
  • Peptide Hydrolases
  • Calpain
  • Calcium