Reconstitution and characterization of two forms of cyclic nucleotide-gated channels from skeletal muscle.
A cyclic nucleotide-gated channel present in skeletal muscle plasma membrane has previously been identified as being responsible for insulin-activated sodium entry into muscle cells (J. E. M. McGeoch and G. Guidotti. J. Biol. Chem. 267:832-841, 1992). We have isolated this channel activity to further study and characterize it. The channel was solubilized from rabbit skeletal muscle sarcolemma and functionally reconstituted into phospholipid vesicles, as assayed by patch-clamp analysis of the reconstituted proteins. Channel activity was isolated by 8-bromo-guanosine 3',5'-cyclic monophosphate affinity chromatography, producing two distinct peaks of cyclic nucleotide-gated channel activity. These two types of channel activity differ in guanosine 3',5'-cyclic monophosphate affinity and in the ability to be opened by adenosine 3',5'-cyclic monophosphate. The cyclic nucleotide-gated channel from rod outer segments also forms two peaks of activity when purified in this manner. The presence of two forms of channel activity could have implications for the mechanism of insulin-activated sodium entry.
Santy
L C
LC
Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
Guidotti
G
G
D000818:Animals; D002462:Cell Membrane / Q000378:metabolism; D015640:Ion Channel Gating; D007473:Ion Channels / Q000032:analysis* / Q000302:isolation & purification; D018482:Muscle, Skeletal / Q000378:metabolism*; D009712:Nucleotides, Cyclic / Q000378:metabolism*; D018408:Patch-Clamp Techniques; D011817:Rabbits
D007473:Ion Channels; D009712:Nucleotides, Cyclic