Prolonged exposure of hamsters to cold changes the levels of g proteins in brown adipose tissue plasma membranes

Abstract

The levels of G proteins in plasma membranes prepared from brown adipose tissue of control and cold-exposed hamsters were determined by quantitative immunoblotting and competitive ELISA. Prolonged (four weeks) exposure of hamsters to cold decreased significantly the total content of the a subunits of the stimulatory (G sα) as well as inhibitory (G iα(1,2)) G proteins. Interestingly, the reduction in the G sα content was solely due to a large reduction in the content of the short (45 kDa) isoform of G sα, while the level of the long (52 kDa) isoform of G sα remained unchanged. The level of the β subunit of G protein was decreased comparably to the reduction in the total content of the a subunits. Cold-induced alterations in the G protein network associated with plasma membranes of brown adipose tissue were accompanied by changed characteristics of A1F 4 − -sensitive adenylyl cyclase activity.