Protein phosphorylation of synaptic membranes isolated from the brain of ground squirrels during hibernation.

In vitro protein phosphorylation of synaptic membranes isolated from neocortex and hippocampus of ground squirrels was studied. Three functional states of animals were investigated: torpid, awakened and active normothermic. Phosphorylation of a protein with a mol. wt of 53 kDa was independent on the functional state of the animals. Incorporation of 32P into this protein was greater in membranes of torpid and awakened squirrels than in membranes of active animals. These results suggest that protein phosphorylation is involved in the maintenance of membrane functions during hibernation.