A calmodulin dependent Ca2+-activated K+ channel in the adipocyte plasma membrane |
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| Authors: | H A Pershadsingh R D Gale D M Delfert J M McDonald |
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| Institution: | 1. Division of Laboratory Medicine, Department of Pathology Washington University School of Medicine St. Louis, Missouri 63110 USA;2. Department of Medicine Washington University School of Medicine St. Louis, Missouri 63110 USA;3. Barnes Hospital St. Louis, Missouri 63110 USA;1. Department of Human Health and Nutritional Sciences, University of Guelph, 50 Stone Rd. E., Guelph, ON, Canada N1G2W1;2. Division of Nutritional Sciences, University of Illinois, 905 South Goodwin Avenue, Urbana, IL 61801, USA;1. Department of Orthopedic Surgery and Institute of Health Sciences, Gyeongsang National University School of Medicine and Gyeongsang National University Hospital, Jinju, Republic of Korea;2. School of Biosystem and Biomedical Science, College of Health Science, Korea University, Seoul, 02841, Republic of Korea |
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| Abstract: | Increased membrane permeability (conductance) that is specific for K+ and directly activated by Ca2+ ions, has been identified in isolated adipocyte plasma membranes using the K+ analogue, 86Rb+. Activation of these K+ conductance pathways (channels) by free Ca2+ was concentration dependent with a half-maximal effect occurring at 32 +/- 4 nM free Ca2+ (n = 7). Addition of calmodulin further enhanced the Ca2+ activating effect on 86Rb+ uptake (K+ channel activity). Ca2+-dependent 86Rb+ uptake was inhibited by tetraethylammonium ion and low pH. It is concluded that the adipocyte plasma membrane possesses K+ channels that are activated by Ca2+ and amplified by calmodulin. |
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