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Full-Text Articles in Molecular Biology
Short-Term Feedback Regulation Of Camp By Accelerated Degradation In Rat Tissues, Tom W. Gettys, Peter F. Blackmore, J. Bruce Redmon, Stephen J. Beebe, Jackie D. Corbin
Short-Term Feedback Regulation Of Camp By Accelerated Degradation In Rat Tissues, Tom W. Gettys, Peter F. Blackmore, J. Bruce Redmon, Stephen J. Beebe, Jackie D. Corbin
Bioelectrics Publications
A recent study showed that cAMP analogs lowered cAMP levels in rat hepatocytes. The present work demonstrates that cAMP analogs also lowered cAMP in a rapid, concentration-dependent manner in heart and fat cells. In order to determine if the cAMP-dependent protein kinase mediated this effect, techniques were developed to assay the protein kinase activity ratio in hepatocytes treated with cAMP analogs. The activation of protein kinase and phosphorylase in hepatocytes by 8-pClΦS-cAMP (where 8-pClΦS- indicates 8-parachlorothiophenyl-) was concentration-dependent and occurred in parallel to proportionate decreases in cAMP. More than 20% of the cAMP binding sites on the protein kinase were …
Camp-Dependent Protein Kinase Activation Lowers Hepatocyte Camp, Jackie D. Corbin, Stephen J. Beebe, Peter F. Blackmore
Camp-Dependent Protein Kinase Activation Lowers Hepatocyte Camp, Jackie D. Corbin, Stephen J. Beebe, Peter F. Blackmore
Bioelectrics Publications
Rat hepatocyte protein kinase was activated by incubating the cells with various cAMP analogs. Boiled extracts were then prepared and Sephadex G-25 chromatography was carried out. The G-25 procedure separated the analogs from cAMP since the resin had the unexpected property of binding cyclic nucleotides with differing affinities. Separation was necessary because the analogs would otherwise interfere with the sensitive protein kinase activation method developed for assay of cAMP. The cAMP analogs, but not 5'-AMP, lowered basal cAMP by 50-70%. The effect was rapid, analog concentration-dependent, and occurred parallel with phosphorylase activation, suggesting that the cAMP analogs act through cAMP-dependent …
Two Classes Of Camp Analogs Which Are Selective For The Two Different Camp-Binding Sites Of Type Ii Protein Kinase Demonstrate Synergism When Added Together To Intact Adipocytes, Stephen J. Beebe, Rob Holloway, Stephen R. Rannels, Jackie D. Corbin
Two Classes Of Camp Analogs Which Are Selective For The Two Different Camp-Binding Sites Of Type Ii Protein Kinase Demonstrate Synergism When Added Together To Intact Adipocytes, Stephen J. Beebe, Rob Holloway, Stephen R. Rannels, Jackie D. Corbin
Bioelectrics Publications
Twenty-five cyclic nucleotide analogs were tested individually to act as lipolytic agents and to activate adipocyte protein kinase. The lipolytic potency of individual analogs correlated better with their K(a) for protein kinase and their lipophilicity rather than with either parameters alone. Some of the most potent lipolytic analogs had high I50 values for the particulate low K(m) cAMP phosphodiesterase suggesting that their effect was not due to raising endogenous cAMP levels through inhibition of phosphodiesterase. The most potent lipolytic analogs contained a thio moiety at the C-8 or C-6 position. These analogs exhibited concave upward dose-response curves. At high concentrations …