Mezerein and 12-deoxyphorbol 13-isobutyrate, protein kinase C ligands with differential biological activities, do not distinguish PKC-isotypes alpha, beta 1, beta 2, and gamma.
Previous in vitro experiments have shown that the phorbol-like diterpenes 12-deoxyphorbol 13-isobutyrate (dPB), and possibly mezerein, have multiple biological target sites which differ from one another in apparent affinity for dPB by 12.5-780 fold and for mezerein by 24-fold. These two compounds are thus very important ligands because of their potential PKC isotype-selectivity. In the present study they were found to have binding affinities differing by a maximum of only 1.6-fold among recombinant protein kinase C (PKC) isotypes alpha, beta 1, beta 2, and gamma (the "A-group") in a [3H]phorbol dibutyrate binding assay. The apparent Ki's were 92-140 nM for dPB and 68-92 nM for mezerein. Our results are consistent with short-term 12-deoxyphorbol ester-induced mouse skin inflammation being mediated at least in part by one or more A-group PKC isotypes. The data also indicate that the pharmacologically distinguishable target sites previously established for mezerein and dPB must include one or more binding sites not found in the A-group of PKC isotypes and that mezerein has a high-affinity, non-A-group target site in brain.
Driedger
P E
PE
Procyon Pharmaceuticals, Inc., Woburn, MA 01801.
Stabel
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S
Frith
D
D
Horgan
T J
TJ
D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000201:enzymology*; D002417:Cattle; D002460:Cell Line; D003600:Cytosol / Q000201:enzymology; D004224:Diterpenes; D005260:Female; D006801:Humans; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism*; D007700:Kinetics; D008024:Ligands; D051379:Mice; D008815:Mice, Inbred Strains; D015240:Phorbol 12,13-Dibutyrate / Q000378:metabolism; D010703:Phorbol Esters / Q000378:metabolism* / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D018411:Spodoptera; D013729:Terpenes / Q000378:metabolism* / Q000494:pharmacology; D014162:Transfection
D004224:Diterpenes; D007527:Isoenzymes; D008024:Ligands; D010703:Phorbol Esters; D011994:Recombinant Proteins; D013729:Terpenes; C039067:12-deoxyphorbol 13-isobutyrate; C011309:mezerein; D015240:Phorbol 12,13-Dibutyrate; D011493:Protein Kinase C