Kinetic variability and modulation of dSlo, a cloned calcium-dependent potassium channel.
We have examined, using patch recording, the modulation by ATP gamma S of the cloned Drosophila slopoke calcium-dependent potassium channel (dSlo) expressed in Xenopus oocytes. There is a large variation in the gating kinetics, open probability, and conductance level of the channel in this expression system, which complicates the analysis of modulatory events. Addition of ATP gamma S to the intracellular face of the patch does not consistently alter the overall open probability of dSlo, but it does increase the frequency of appearance of an exceptionally long-lived closed state of the channel. This modulation is not blocked by an inhibitor of several serine/threonine protein kinases, nor by mutation of a serine residue that is a target for phosphorylation by protein kinase A. Thus, ATP gamma S may alter dSlo kinetic properties by some mechanism other than serine/threonine phosphorylation.
Bowlby
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MR
Biochemistry Department, Brandeis University, Waltham, MA 02254, USA.
Levitan
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IB
D000255:Adenosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D000818:Animals; D015640:Ion Channel Gating / Q000187:drug effects*; D007700:Kinetics; D051036:Large-Conductance Calcium-Activated Potassium Channels; D009865:Oocytes / Q000378:metabolism; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000096:biosynthesis / Q000378:metabolism*; D024681:Potassium Channels, Calcium-Activated; D014982:Xenopus laevis
D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; C022571:adenosine 5'-O-(3-thiotriphosphate); D000255:Adenosine Triphosphate