AJP - Endocrinology and Metabolism, Vol 248, Issue 1 31-E35, Copyright © 1985 by American Physiological Society
Effects of benzyl alcohol on PTH receptor-adenylate cyclase system of canine kidney
K. J. Martin, C. L. McConkey Jr and T. J. Stokes Jr
In many systems, perturbations of membrane architecture by changes of lipid
and phospholipid composition have been shown to alter the activity of
membrane-bound enzymes. The present studies examined the effect of benzyl
alcohol, an agent that has been shown to increase membrane fluidity, on the
parathyroid hormone (PTH)-sensitive adenylate cyclase system of canine
kidney. Benzyl alcohol progressively increased basal adenylate cyclase
activity up to fourfold and maximal enzyme activity in the presence of PTH,
GTP, guanylimidodiphosphate, and sodium fluoride by four- to sixfold. In
the presence of 20 mM Mn2+ (no Mg2+), conditions under which enzyme
activity is devoid of influence of guanine nucleotides or hormones, benzyl
alcohol was without effect. PTH binding was increased by 25% in the
presence of benzyl alcohol without a change in binding affinity.
Fluorescent polarization studies using diphenylhexatriene showed a decrease
in fluorescence anisotropy in the presence of benzyl alcohol. The results
suggest that benzyl alcohol facilitates the interaction of the components
of the adenylate cyclase system, presumably by increasing membrane
fluidity. Alterations of membrane fluidity may be a potent means of
regulating hormone sensitive adenylate cyclase activity.
