PIP2 modulation of Slick and Slack K+ channels

Slick and Slack are members of the Slo family of high-conductance potassium channels. These channels are activated by Na+ and Cl− and are highly expressed in the CNS, where they are believed to contribute to the resting membrane potential of neurons and the control of excitability. Herein, we provide evidence that Slick and Slack channels are regulated by the phosphoinositide PIP2. Two stereoisomers of PIP2 were able to exogenously activate Slick and Slack channels expressed in Xenopus oocytes, and in addition, it is shown that Slick and Slack channels are modulated by endogenous PIP2. The activating effect of PIP2 appears to occur by direct interaction with lysine 306 in Slick and lysine 339 in Slack, located at the proximal C-termini of both channels. Overall, our data suggest that PIP2 is an important regulator of Slick and Slack channels, yet it is not involved in the recently described cell volume sensitivity of Slick channels, since mutated PIP2-insensitive Slick channels retained their sensitivity to cell volume.

► Slick (Slo2.1) and Slack (Slo2.2) K+ channels are expressed in CNS and the heart.
► The channels control basal excitability and are involved in cell volume regulation.
► Slick and Slack channels are regulated by PI(4,5)P2 and PI(3,4)P2.
► Specific lysines in the C-termini of the channels are involved in PIP2 binding.
► PIP2 is not involved in the regulation of Slick channels by cell volume.