Recent biochemical, immunochemical and molecular biology studies indicate that this channel consists of a complex of two distinct subunits and one or more associated proteins. The latter two features are found in voltage-gated channels and suggest that these two classes of channels have evolved from the same ancestral channel protein. A working model for the membrane topography of the channel subunits is proposed based on immunogold labeling studies and sequence analysis. Author to whom correspondence should be addressed. Please do not prepare a commentary on the electronic drafts.
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