Structure of a voltage-dependent K+ channel beta subunit.
The integral membrane subunits of many voltage-dependent potassium channels are associated with an additional protein known as the beta subunit. One function of beta subunits is to modify K+ channel gating. We have determined the structure of the conserved core of mammalian beta subunits by X-ray crystallography at 2.8 A resolution. Like the integral membrane component of K+ channels, beta subunits form a four-fold symmetric structure. Each subunit is an oxidoreductase enzyme complete with a nicotinamide co-factor in its active site. Several structural features of the enzyme active site, including its location with respect to the four-fold axis, imply that it may interact directly or indirectly with the K+ channel's voltage sensor. This structure suggests a mechanism for coupling membrane electrical excitability directly to chemistry of the cell.
Gulbis
J M
JM
Laboratory of Molecular Neurobiology and Biophysics and the Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021, USA.
Mann
S
S
MacKinnon
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004553:Electric Conductivity; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000737:chemistry*; D011487:Protein Conformation; D017386:Sequence Homology, Amino Acid
D015221:Potassium Channels