Phosphorylation of Synaptic Membranes

Abstract

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 :3ZPi-orthophosphate. After a 40-min isotope incorporation period, rats were decapitated and synaptic membranes isolated. In ilitro phosphorylation was accomplished by incubating unlabeled synaptic membranes, isolated from noninjected rats, with 5 ~M-[~-"'P]ATP. In viva and in vitro :32P-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 vifro "P-labeled synaptic membranes were identical. In contrast, autoradiographs of these gels showed striking differences in the pattern of phosphate incorporation. Cyclic-AMP (10 p~) maximally stimulated the in vitro phosphate labeling of two protein bands (80,000 and 55,000 apparent molecular weight) which were not substantially labeled by the in viva p r o c e d u r e . K e y w o r d s : S y n a p t i c m e m b r a n e s -B r a i n p r o t e i n phosphorylation-Protein phosphorylation in viw-Membrane protein phosphorylation.

Hydrophilic interaction liquid chromatography/mass spectrometry for determination of domoic acid in Adriatic shellfish

“…Domoic acid binds predominantly to N ‐methyl‐D‐aspartate (NMDA) receptors in the central nervous system, resulting in depolarization of neurons. Subsequently, the permeability to calcium ions increases, leading to cell dysfunction or death 2…”

The Phosphorylation of Proteins in Hippocampal Slices: Effects of Noradrenaline and of Pretreatment with Kainic Acid

“…It was only under post hoc conditions of phosphorylation that cyclic AMP was found to be effective in a manner similar to that found with in vitm phosphorylation of membrane preparations (Forn and Greengard, 1978). Moreover, Berman et al (1980) compared the in vivo and in vitro phosphorylation of synaptosomal membrane proteins and found discrepancies regarding proteins whose phosphorylation is cyclic AMP dependent. This complexity had already been discussed by Hullihan et al (1977), who failed to show dopamine-stimulated phosphorylation in homogenates of rat caudate nucleus, as well as by Brunton et al (1979), who failed to find any correlation between isoprenaline and prostaglandin Elstimulated cyclic AMP formation and phosphorylation of perfused heart proteins.…”