Gating mode conversion by proteolysis in a large-conductance K+ channel from embryonic rat telencephalon.
1. In situ patch-clamp recordings of early embryonic large-conductance K+ channels consistently revealed (86% of patches) a complex behaviour characterized by noisy fluctuations between open and closed states of relatively short duration. 2. This behaviour is similar to the buzz mode, a type of gating observed only very rarely in some channels. Its prevalence in proliferative neuroepithelium may thus constitute a criterion of immaturity. 3. In 89% of patches, the buzz mode was converted to a 'normal' mode by intracellular exposure to trypsin. 4. These observations suggest that the immature channel protein includes (or is affected by) a cytoplasmic component, the presence or absence of which determines certain sets of conformational transitions.
Mienville
J M
JM
Laboratory of Neurophysiology, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
D000818:Animals; D002118:Calcium / Q000502:physiology; D005260:Female; D006868:Hydrolysis; D066298:In Vitro Techniques; D015640:Ion Channel Gating / Q000502:physiology*; D007700:Kinetics; D008564:Membrane Potentials / Q000187:drug effects; D018408:Patch-Clamp Techniques; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013687:Telencephalon / Q000166:cytology / Q000196:embryology / Q000378:metabolism*; D014357:Trypsin / Q000494:pharmacology*
D015221:Potassium Channels; D014357:Trypsin; D002118:Calcium