CaM dependent kinases

If beta cells are incubated in media containing 2 mM glucose and then treated with forskolin and/or tolbutamide, there is a small transient increase in insulin secretion. The subsequent addition of CCK8S leads to a very marked first phase of insulin secretion, but causes no sustained increase or second phase of insulin secretion. These results mean that an increase in cAMP alters the Ca2+ sensitivity of the response elements underlying the first phase of secretion. These elements, presumed to be Ca2+-calmodulin-dependent processes including CaM-dependent protein kinases, become more sensitive to activation by Ca2+ either because cAMP acts to enhance the sensitivity of CaM-dependent kinases to Ca2+, or because cAMP inhibits, by an unknown mechanism, the activity of phosphoprotein phosphatases. 

The integrated cellular response of the adrenal glomerulosa cell is determined by the activities of three different protein kinases cAMP-dependent protein kinase, CaM-dependent protein kinases, and C-kinase. A sustained response can be produced by the combined activation either of the cAMP- and CaM-dependent kinases, or of the CaM-dependent kinases and C-kinase. Activation of each type of... 

Calmodulin dependent Kinases. Calmodulin-dependent kinases further relay and amplify the calcium signal from calmodulin to their target proteins. In animals, the identified calmodulin-dependent kinases include CaM-dependent kinase kinase (CaMKK), CaM kinase I-IV (CaMKI-IV), in which CaMKII is also known as elongation factor-2 kinase (eEF 2K), MLCKs and so on. CaMKK, CaMKI, CaMKII, and CaMKIV have multiple targets that involve them in multiple activities, while eEF-2K and MLCK have much more restricted targets. CaMKK is at the upstream of the CaMKI and CaMKIV kinase cascade. CaMKK activates CaMKI and CaMKIV through the phosphorylation of these two kinases. The other substrate for CaMKK is protein kinase B (PKB). The activity of CaMKK itself is inhibited by protein... 

B. Ca -calmodnlin (CaM)-dependent Phosphorylase kinase (PhK) —krk qis vrgl— phosphorylation by PKA... 

Other studies have demonstrated that the skeletal muscle ai peptide can be phosphorylated in T-tubule membranes by a multifunctional Ca " /calmodulin (CaM)-dependent protein kinase [111], Phosphorylation occurs on the i subunit to an extent of 2 mol phosphate/mol subunit and on the /i subunit to an extent of 0.7-1 mol phosphate/mol channel [108,111]. Phosphorylation catalyzed by the CaM-kinase on the ai subunit is additive to that caused by PKA and occurs on distinct sites [111]. So far, however, we have not observed any functional consequences of phosphorylation of the skeletal muscle Ca channels by the CaM-kinase. 

Ca2+-CaM-dependent Protein Kinase Ca2+-dependent Protein Kinase Central Nervous System... 

Meanwhile, the polar IP3 moiety binds to intracellular receptors on the endoplasmic reticulum, resulting in the liberation of calcium into the cytosol. The calcium binds to calmodulin, which then activates another group of protein kinases (the Ca2+/CaM-dependent protein kinases). Hormonal stimulation can be short-lived because IP3 and DG are rapidly degraded to inactive forms that are ultimately recycled to PIP2 Ca2+ is pumped back into the endoplasmic reticulum, where it is sequestered. 

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