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.
Laboratory of Molecular Neurobiology and Biophysics and the Howard Hughes Medical Institute, Rockefeller University, New York, New York 10021, USA.
J M
JM
Gulbis
S
S
Mann
R
R
MacKinnon
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