Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.11.13 (protein kinase C)
 49,245 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

GAP-43 is a neuronal calmodulin-binding phosphoprotein that is concentrated in growth cones and presynaptic terminals. By sequencing tryptic and endoproteinase Asp-N phosphopeptides and directly determining the release of radioactive phosphate, we have identified three sites (serines 41 and 96 and threonine 172) that are phosphorylated, both in cultured neurons and in neonatal rat brain. These three sites account for most of the 32PO4 that was incorporated into GAP-43 in cultured neurons; 8-15% of each site was occupied with phosphate in GAP-43 isolated from neonatal rat brain. Phosphorylation of serine 41 in cultured neurons was stimulated by phorbol ester, indicating that it is the only site phosphorylated by protein kinase C. The resemblance of the sequence surrounding the other two sites suggests that they may be substrates for the same protein kinase. None of the sites phosphorylated by casein kinase II in vitro was phosphorylated in living cells or in neonatal rat brain. These results show that GAP-43 is a substrate for at least one protein kinase in addition to protein kinase C in living cells and brain.
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PMID:GAP-43, a protein associated with axon growth, is phosphorylated at three sites in cultured neurons and rat brain. 153 24

The protein kinase C phosphorylation sites on bovine rhodopsin were identified using proteolytic, phosphoamino acid, mass spectrometric, and peptide sequencing analyses. Tryptic removal of the 9 carboxyl-terminal residues of rhodopsin revealed that a major fraction of the phosphates incorporated by protein kinase C are in a region containing Ser334, Thr335, and Thr336. Phosphoamino acid analysis of the tryptic product established that Ser334 accounts for approximately 65% of the phosphorylation in this region. Analysis of the endoproteinase Asp-N-generated carboxyl terminus of rhodopsin by mass spectrometry and peptide sequencing revealed that Ser338 is also a primary phosphorylation site, with minor phosphorylation of Ser343. Quantitation of high pressure liquid chromatography-separated phosphopeptides, taken together with phosphoamino acid analysis of the tryptic product, revealed that Ser334 and Ser338 were phosphorylated equally and each accounted for approximately 35% of the total phosphorylation; Thr335/336 accounted for just under 20% of the phosphorylation, and Ser343 accounted for 10%. Thus, the primary protein kinase C sites are Ser334 and Ser338, with minor phosphorylation of Thr335/336 and Ser343. Ser334 and Ser338 have recently been identified as the primary sites of phosphorylation of rhodopsin in vivo (Ohguro, H., Van Hooser, J. P., Milam, A. H., and Palczewski, K. (1995) J. Biol. Chem. 270, 14259-14262). Of these sites, only Ser338 is a significant substrate for rhodopsin kinase in vitro. Identification of Ser334 as a primary protein kinase C target in vitro is consistent with protein kinase C modulating the phosphorylation of this site in vivo.
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PMID:Identification of protein kinase C phosphorylation sites on bovine rhodopsin. 909 69

Hippocampal long-term potentiation (LTP) is a long-lasting and rapidly induced increase in synaptic strength. Previous experiments have determined that persistent activation of protein kinase C (PKC) contributes to the early maintenance phase of LTP (E-LTP). Using the back-phosphorylation method, we observed an increase in the phosphorylation of a 21-kDa PKC substrate, termed p21, 45 min after LTP was induced in the CA1 region of the hippocampus. p21 was found to have the same apparent molecular weight as the 18.5-kDa isoform of myelin basic protein (MBP) and was recognized by an antibody to MBP in western blotting and immunoprecipitation. Furthermore, p21 from control and potentiated hippocampal slices and purified MBP have identical phosphopeptide maps when back-phosphorylated and then digested with either endoproteinase Lys-C or endoproteinase Asp-N, suggesting that p21 and MBP are identical proteins. As there was no observed change in the amount of MBP in LTP, the increase in MBP phosphorylation during LTP cannot be explained by a change in the amount of protein. From these experiments, we conclude that the phosphorylation of the 18.5-kDa isoform of MBP is increased during E-LTP.
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PMID:Increased phosphorylation of myelin basic protein during hippocampal long-term potentiation. 910 22