Preliminary characterization of calcium binding in islet-cell plasma membranes

Diabetologia. 1980 Nov;19(5):439-44. doi: 10.1007/BF00281823.


Preliminary characterization of calcium binding was determined in a highly-enriched islet-cell plasma membrane fraction using a membrane filtration technique. Equilbrium calcium binding was specific, concentration dependent and saturable. Scatchard analysis indicated the existence of more than one class of calcium binding sites. The affinity constants and maximum binding capacities were 1.14 X 10(5) M-1 and 1.2 picomol/microgram protein and 1.17 X 10(3) M-1 and 64.8 picomol/microgram for the high and low affinity sites, respectively. Bound 45Ca2+ was dissociate from the plasma membranes in a biphasic manner in the presence of excess unlabelled calcium.

Publication types

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

MeSH terms

  • Animals
  • Binding Sites
  • Calcium / metabolism
  • Calcium Radioisotopes
  • Cell Fractionation
  • Cell Membrane / metabolism*
  • Insulin / metabolism
  • Insulin Secretion
  • Islets of Langerhans / metabolism*
  • Rats


  • Calcium Radioisotopes
  • Insulin
  • Calcium