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Mutations in the Intracellular Cavity of Shaker K+ Channels Alter the Kinetics of N-type Inactivation


Adam Lowet Photo

Walt Whitman High School (Maryland)

Neurons depend on voltage-gated ion channels for the propagation of action potentials following membrane depolarization. Certain potassium channels can modulate firing frequency by closing rapidly after opening, in a process called inactivation. Structural and functional studies of Shaker and human KV channels have revealed that such inactivation can be described according to a “ball-and-chain” model, with the protein’s cytoplasmic amino terminus forming the “ball.” The ball is attached to a long, flexible peptide “chain” and binds to a receptor site within the pore, cutting off ion flow. It has been proposed that this process occurs through sequential steps, in which the inactivation ball binds initially to the cytoplasmic channel surface and then enters the pore as an extended peptide. Here, we offer support to this theory and characterize the interaction using mutagenesis and electrophysiological methods

Last updated November 27, 2013