In vivo and in vitro phosphorylation of synaptic membrane proteins were compared. In vivo phosphorylation was carried out by injecting rats intraventricularly with 1 mCi of 32P1-orthophosphate. After a 40-min isotope incorporation period, rats were decapitated and the synaptic membranes isolated. In vitro phosphorylation was accomplished by incubating unlabeled synaptic membranes, isolated from noninjected rats, with 5 μM-[γ-32P]ATP. In vivo and in vitro 32 P-labeled synaptic membranes were then fractionated electrophoretically on an SDS-polyacrylamide (7.5%) slab gel. The Coomassie blue protein patterns for in vivo and in vitro 32 P-labeled synaptic membranes were identical. In contrast, autoradiographs of these gels showed striking differences in the pattern of phosphate incorporation. Cyclic-AMP (10 μM) maximally stimulated the in vitro phosphate labelling of two protein bands (80,000 and 55,000 apparent molecular weight) which were not substantially labeled by the in vivo procedure.
|Original language||English (US)|
|Number of pages||7|
|Journal||Journal of Neurochemistry|
|State||Published - 1980|
ASJC Scopus subject areas
- Cellular and Molecular Neuroscience