AJP - Endocrinology and Metabolism, Vol 255, Issue 6 E865-E870, Copyright © 1988 by American Physiological Society
Changes in GDP binding to brown adipose tissue mitochondria and the uncoupling protein
A. G. Swick and R. W. Swick
Department of Nutritional Sciences, University of Wisconsin-Madison 53706.
Incubation in vitro of brown adipose tissue (BAT) mitochondria with
divalent cations, spermine, or alkaline phosphatase led to a marked
increase in the binding of [3H]GDP. The effect of Mg2+ appeared to be the
most specific and led to the largest increase in GDP binding. A simplified
method was developed for measuring GDP binding to purified uncoupling
protein from rat BAT mitochondria. Application of this method indicates
that uncoupling protein from cold-acclimated rats binds twice as much GDP
as uncoupling protein from cold-acclimated rats that were briefly returned
to thermoneutrality, paralleling changes in GDP binding to the
mitochondria. Incubation of BAT mitochondria with Mg2+ led to a smaller
increase in GDP binding to the subsequently purified uncoupling protein,
suggesting that divalent cations may somehow participate in the regulation
of the activity of the uncoupling protein.
