Effects of polymyxin B on the sarcoplasmic reticulum membrane.
Polymyxin B, a cyclic peptide antibiotic, inhibits Ca2+-ATPase, p-nitrophenyl phosphatase and phosphorylase kinase activities associated with rabbit skeletal muscle sarcoplasmic reticulum membranes; 50% inhibition is induced by 100 microM, 130 microM and 550 microM of polymyxin respectively. The fluorescence intensity of fluorescein isothiocyanate-labeled Ca2+-ATPase, decreases in the presence of polymyxin (50% of the total decrease at 70 microM polymyxin). On the other hand, the polypeptide inhibits calmodulin-dependent endogenous phosphorylation of 60 kDa, 20 kDa and 14 kDa membrane proteins, while an increase of calmodulin-dependent phosphorylation is observed in 132 kDa and 86 kDa proteins.
Ktenas
T B
TB
Institute of Biological Research, National Hellenic Research Foundation, Athens, Greece.
Sotiroudis
T G
TG
Evangelopoulos
A E
AE
D009597:4-Nitrophenylphosphatase / Q000037:antagonists & inhibitors; D000818:Animals; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002147:Calmodulin / Q000494:pharmacology; D066298:In Vitro Techniques; D007425:Intracellular Membranes / Q000187:drug effects / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D010764:Phosphorylase Kinase / Q000037:antagonists & inhibitors; D011112:Polymyxin B / Q000494:pharmacology*; D011113:Polymyxins / Q000494:pharmacology*; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism
D002147:Calmodulin; D008565:Membrane Proteins; D011113:Polymyxins; D010764:Phosphorylase Kinase; D009597:4-Nitrophenylphosphatase; D000252:Calcium-Transporting ATPases; D011112:Polymyxin B