Identification of yeast proteins necessary for cell-surface function of a potassium channel.

Inwardly rectifying potassium (Kir) channels form gates in the cell membrane that regulate the flow of K(+) ions into and out of the cell, thereby influencing the membrane potential and electrical signaling of many cell types, including neurons and cardiomyocytes. Kir-channel function depends on other cellular proteins that aid in the folding of channel subunits, assembly into tetrameric complexes, trafficking of quality-controlled channels to the plasma membrane, and regulation of channel activity at the cell surface. We used the yeast Saccharomyces cerevisiae as a model system to identify proteins necessary for the functional expression of a mammalian Kir channel at the cell surface.

Merging functional studies with structures of inward-rectifier K(+) channels.

Inwardly rectifying K(+) (Kir) channels have a wide range of functions including the control of neuronal signalling, heart rate, blood flow and insulin release. Because of the physiological importance of these channels, considerable effort has been invested in understanding the structural basis of their physiology. In this review, we use two recent, high-resolution structures as foundations for examining our current understanding of the fundamental functions that are shared by all K(+) channels, such as K(+) selectivity and channel gating, as well as characteristic features of Kir channel family members, such as inward rectification and their regulation by intracellular factors.