Calcium-dependent interactions of an ionophore A23187 with calmodulin.
We found that ionophore A23187 interacted reversibly with calmodulin (CaM), in a calcium-dependent fashion. It was found that A23187 interacts selectively with CaM, among calcium binding proteins (such as troponin C and S-100 protein) and other proteins. However, apparently differing from W-7, A23187 did not suppress CaM-dependent enzyme activity such as myosin light chain kinase and Ca2+-dependent cyclic nucleotide phosphodiesterase. Our observations suggest that there are novel calcium-dependent regions of CaM which can be monitored using ionophore A23187 and may not be related to enzyme activation.
D000818:Animals; D000001:Calcimycin / Q000378:metabolism; D002118:Calcium; D002135:Calcium-Binding Proteins; D002147:Calmodulin / Q000378:metabolism; D002478:Cells, Cultured; D008566:Membranes / Q000378:metabolism; D009130:Muscle, Smooth / Q000378:metabolism; D009529:Nicardipine; D009543:Nifedipine / Q000031:analogs & derivatives / Q000378:metabolism; D011485:Protein Binding; D011506:Proteins; D011817:Rabbits; D012995:Solubility; D013050:Spectrometry, Fluorescence
D002135:Calcium-Binding Proteins; D002147:Calmodulin; D011506:Proteins; D000001:Calcimycin; D009529:Nicardipine; D009543:Nifedipine; D002118:Calcium