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)

Type-2 calcium-dependent potassium (KCa) channels from mammalian brain, reconstituted into planar phospholipid bilayers, are modulated by ATP or ATP analogs via an endogenous protein kinase activity intimately associated with the channel (Chung et al., 1991). We show here that the endogenous protein kinase activity is protein kinase C (PKC)-like because (1) modulation by ATP can be mimicked by exogenous PKC, and (2) the effects of ATP can be blocked by PKC(19-36), a specific peptide inhibitor of PKC. Furthermore, adding the PKC inhibitor peptide after the addition of ATP reverses the modulation produced by ATP, suggesting that there is a phosphoprotein phosphatase activity closely associated with type-2 KCa channels. Consistent with this idea is the finding that microcystin, a non-specific phosphatase inhibitor, enhances the modulation of KCa channel activity by ATP. Inhibitor-1, a specific protein inhibitor of phosphoprotein phosphatase-1, also enhances the effect of ATP, suggesting that the endogenous phosphatase activity is phosphatase-1-like. The results imply that type-2 KCa channels exist as part of a regulatory complex that includes a PKC-like protein kinase and a phosphatase-1-like phosphoprotein phosphatase, both of which participate in the modulation of channel function.
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PMID:Kinase and phosphatase activities intimately associated with a reconstituted calcium-dependent potassium channel. 779 Sep 24

In the present study, the role of phosphoprotein phosphatase in the regulation of L-type Ca2+ channel currents in rat pinealocytes was investigated using the whole-cell version of the patch-clamp technique. The effects of three phosphatase inhibitors, calyculin A, tautomycin, and okadaic acid, were compared. Although all three inhibitors were effective in inhibiting the L-type Ca2+ channel current, calyculin A was more potent than either tautomycin or okadaic acid, suggesting the involvement of phosphoprotein phosphatase-1. To determine the kinase involved in the regulation of these channels, cells were pretreated with H7 (a nonspecific kinase inhibitor), H89 (a specific inhibitor of cyclic AMP-dependent kinase), KT5823 (a specific inhibitor of cyclic GMP-dependent kinase), or calphostin C (a specific inhibitor of protein kinase C). Pretreatment with either H7 or calphostin C decreased the inhibitory effect of calyculin A on the L-type Ca2+ channel current. In contrast, pretreatment with H89 or KT5823 had no effect on the inhibition caused by calyculin A. Based on these observations, we conclude that basal phosphatase activity, probably phosphoprotein phosphatase-1, plays an important role in the regulation of L-type Ca2+ channel currents in rat pinealocytes by counteracting protein kinase C-mediated phosphorylation.
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PMID:Regulation of the L-type Ca2+ channel current in rat pinealocytes: role of basal phosphorylation. 988 56