Ontogeny of Membrane-Bound Protein Phosphorylating Systems in the Rat
The ontogeny of the major protein phosphorylating systems in membrane fragments from the cerebral cortex was studied in the rat, a species in which synaptogenesis predominantly occurs after birth. The phosphorylation of certain proteins associated with kinase activity largely dependent on either cyclic AMP or Ca2+ (in the presence of calmodulin) increased. The activity changed markedly during the period of 1015 days after birth, i.e. coinciding with the onset of major synaptogenesis. However, the activity of other systems controlled by these factors increased more gradually from birth to adulthood. In contrast, the activity of a phosphorylating system transferring to a protein of 47K daltons in a reaction dependent on Ca2+ only, was abundant at birth and until 15 days of age, but had decreased some 5-fold by the time adulthood was reached.
KeywordsMembrane Fragment Synaptic Membrane Synaptic Plasma Membrane Synaptic Junction Phosphate Acceptor
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