Human brain protein phosphorylation in vitro: cyclic AMP stimulation of electrophoretically-separated substrates.
In vitro phosphorylation of electrophoretically-separated brain proteins was studied in human frontal cortex obtained 3-16 h post-mortem from 13 patients ages 3 days-82 years with extensive, mild or no neuropathological involvement. In 12 of the 13 cases, cyclic AMP increased incorporation of phosphate into acid-precipitable protein. Analysis of the autoradiographic profiles of separate proteins indicated that phosphorylation of the doublet of molecular weight 86-80,000 was stimulated by cyclic AMP in certain samples. This doublet corresponded to the cyclic AMP stimulated doublet from rat frontal cortex we have termed band D-1,2 (proteins Ia and Ib of Ueda and Greengard). Of special interest was the fact that, while co-migration was observed in the other phosphoprotein bands studied, band D-1,2 of humans consistently migrated slightly less than rat protein band D-1,2. This difference was not a function of post-mortem time, subcellular fraction or buffer used in the reaction phosphorylation assay. The use of post-mortem tissue was not a contributing factor as the retardation in band D-1,2 migration was still observed when post-mortem rat brain was used for comparison. In two human post-mortem samples, there was no measureable band D-1,2 phosphorylation even in the presence of cyclic AMP. This was the case in both homogenate and crude synaptosome/mitochondrial preparations. Band F-1 (mol. wt. = 47,000) was not observed in any of the human samples studied. This is consistent with prior studies in rat which show that band F-1 phosphorylation is not detected in post-mortem brain, Band F-2 (mol. wt. 41,000) recently identified as pyruvate dehydrogenase, was lightly phosphorylated under the reaction conditions used in this study.
D000368:Aged; D000375:Aging; D002540:Cerebral Cortex / Q000187:drug effects / Q000254:growth & development / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D000242:Cyclic AMP / Q000494:pharmacology*; D004591:Electrophoresis, Polyacrylamide Gel; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D009419:Nerve Tissue Proteins / Q000378:metabolism*; D010750:Phosphoproteins / Q000302:isolation & purification / Q000378:metabolism*; D010766:Phosphorylation; D011180:Postmortem Changes
D009419:Nerve Tissue Proteins; D010750:Phosphoproteins; D000242:Cyclic AMP