Occurrence of two cholecystokinin binding sites in guinea-pig brain cortex

Biochem Biophys Res Commun. 1986 Jun 30;137(3):1167-73. doi: 10.1016/0006-291x(86)90348-7.


Saturation experiments of the highly potent cholecystokinin analogue [3H]Boc(diNle28,31)CCK27-33 ([3H]BNDL-CCK7, 100 Ci/mmol) with guinea pig brain cortex in a large concentration range (0.05 nM to 30 nM) show the presence of two different binding sites (A site: KD = 0.13 nM, Bmax = 35 fmol/mg; B site: KD = 6.4 nM, Bmax = 92 fmol/mg). Both sites exhibit different sensitivity to sodium ions and therefore can be selectively investigated at [3H]BDNL-CCK7 concentration lower than 1 nM for the A site in Tris buffer and in Krebs buffer for the B site. The selectivity factors KIB/KIA of various CCK related peptides vary from 58 for CCK4 to 26 for CCK8 and 4 for the antagonist (Nle28,31) CCK27-32-NH2. The occurrence of two different CCK binding sites in the brain could explain biphasic pharmacological effects of CCK8.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cerebral Cortex / metabolism*
  • Cholecystokinin / metabolism*
  • Guinea Pigs
  • Kinetics
  • Membranes / metabolism
  • Receptors, Cell Surface / drug effects
  • Receptors, Cell Surface / metabolism*
  • Receptors, Cholecystokinin


  • Receptors, Cell Surface
  • Receptors, Cholecystokinin
  • Cholecystokinin