Structure of a Voltage-Dependent K+ Channel β Subunit

• Published in: Cell Vol. 97; no. 7; pp. 943 - 952
• Main Authors: Gulbis, Jacqueline M, Mann, Sabine, MacKinnon, Roderick
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 25.06.1999
• Subjects: Amino Acid Sequence; Animals; Binding Sites; Crystallography, X-Ray; Electric Conductivity; Humans; Models, Molecular; Molecular Sequence Data; Potassium Channels - chemistry; Protein Conformation; Sequence Homology, Amino Acid
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/S0092-8674(00)80805-3

The integral membrane subunits of many voltage-dependent potassium channels are associated with an additional protein known as the β subunit. One function of β subunits is to modify K+ channel gating. We have determined the structure of the conserved core of mammalian β subunits by X-ray crystallography at 2.8 Å resolution. Like the integral membrane component of K+ channels, β subunits form a four-fold symmetric structure. Each subunit is an oxido-reductase enzyme complete with a nicotinamide cofactor 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.