A calmodulin dependent Ca2+-activated K+ channel in the adipocyte plasma membrane.
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.
H A
HA
Pershadsingh
R D
RD
Gale
D M
DM
Delfert
J M
JM
McDonald
D000273:Adipose Tissue / Q000502:physiology*; D000818:Animals; D002118:Calcium / Q000502:physiology*; D002147:Calmodulin / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology; D002463:Cell Membrane Permeability; D006863:Hydrogen-Ion Concentration; D066298:In Vitro Techniques; D007473:Ion Channels / Q000502:physiology*; D008297:Male; D011188:Potassium / Q000502:physiology*; D051381:Rats; D012413:Rubidium / Q000378:metabolism; D013757:Tetraethylammonium Compounds / Q000494:pharmacology; D014634:Valinomycin / Q000494:pharmacology
D002147:Calmodulin; D007473:Ion Channels; D013757:Tetraethylammonium Compounds; D014634:Valinomycin; D012413:Rubidium; D011188:Potassium; D002118:Calcium