Elsevier

Biochemical Pharmacology

Volume 37, Issue 2, 15 January 1988, Pages 339-347
Biochemical Pharmacology

Purification and characterization of an endogenous protein modulator of radioligand binding to “peripheral-type” benzodiazepine receptors and dihydropyridine ca2+-channel antagonist binding sites

https://doi.org/10.1016/0006-2952(88)90738-1Get rights and content

Abstract

Acidified extracts of rat antral stomach chromatographed on octadecylsilane cartridges contained material that inhibited the binding of [3H]Ro 5-4864 (4'-chlorodiazepam) and [3H]nitrenidipine to “peripheral-type” benzodiazepine receptors and dihydropyridine Ca2+-channel antagonist binding sites respectively. This material reduced the apparent affinites of both radioligands without significantly affecting the maximum number of binding sites. In contrast, the binding of [3H]diazepam, [3H]Ro 15-1788 (ethyl-8-fluoro-5,6-dihydro-5-methyl-6-oxo-4H-imidazo [1,5a][1,4]benzodiazepine-3-carboxylate), and [3H]3-carbomethoxy-β-carboline to “brain-type” benzodiazepine receptors and [3H]dihydroalprenolol binding to β-adrenergic receptors were unaffected by this material. Subsequent column chromatography on hydroxylapatite purified this material by > 2000-fold. This semi-purified substance was resolved by reverse phase HPLC as one u.v. adsorbing peak that inhibited both [3H]Ro 5-4864 and [3H]nitrendipine binding. The activity of this 16,000 dalton substance was destroyed completely by both heat treatment and pronase and partially reduced by trypsin. Furthermore, the inhibitory activity of this substance was enhanced by Ca2+ in a concentration-dependent fashion (0.1 to 10 mM). Comparison of TLC scans of 2–9,10[3H]dipalmitoyl-phosphatidylcholine incubated with either the HPLC purified material or authentic phospholipase A2(PLA2) (Naja naja) revealed that this substance has enzymatic properties indistinguishable from PLA2. These findings suggest that this endogenous protein may be a PLA2 isoenzyme which may modify both “peripheral-type” benzodiazepine receptors and dihydro-pyridine Ca2+-channel antagonist binding sites.

References (40)

  • S.M. Paul et al.

    Eur. J. Pharmac.

    (1981)
  • H. Schoemaker et al.

    Eur. J. Pharmac.

    (1981)
  • J.H. Skerritt et al.

    Neurosci. Lett.

    (1982)
  • J.W. Regan et al.

    Eur. J. Pharmac.

    (1980)
  • B.A. Weissman et al.

    Pharmac. Biochem. Behav.

    (1984)
  • M. Del Zompo et al.

    Life Sci.

    (1984)
  • R.H. Anholt et al.

    Eur. J. Pharmac.

    (1985)
  • A.S. Basile et al.

    Eur. J. Pharmac.

    (1985)
  • M. Dubroeucq et al.

    Eur. J. Pharmac.

    (1986)
  • M. Mestre et al.

    Life Sci.

    (1984)
  • M. Mestre et al.

    Life Sci.

    (1985)
  • C.R. Mantione et al.

    Fedn Eur. Biochem. Soc. Lett.

    (1984)
  • G.D. Swergold et al.

    Analyt. Biochem.

    (1983)
  • O.H. Lowry et al.

    J. biol. Chem.

    (1951)
  • K. Beaumont et al.

    Life Sci.

    (1983)
  • M.E. Goldman et al.

    Life Sci.

    (1985)
  • A.J. Slotboom et al.
  • J.H. Skerritt et al.

    Brain Res.

    (1984)
  • H. Mohler et al.

    Science

    (1977)
  • R.F. Squires et al.

    Nature, Lond.

    (1977)
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    Present address: Merck Sharp & Dohme Research Laboratories, West Point, PA 19486.

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