slob2 is a member the regulatory b subunit family that controls the activity of the large conductance Ca²⁺-activated K⁺ channel K_Ca1.1. This family includes four members with a shared topology: two trans-membrane domains, short intracellular N- and C-termini and a large extracellular region and a distinct tissue distribution.

slob2 expression is relatively broad and includes expression in brain, heart, kidney adrenal chromaffin cells and ovary.

The K_Ca1.1 K⁺ channel can be activated by either an increase in intracellular Ca²⁺ concentration or by membrane depolarization. The regulatory b subunits increase the sensitivity of the pore-forming K_Ca1.1 subunit to Ca²⁺ and membrane voltage and they may also change the channel pharmacology.

The slob2 subunit is unique in that it is able to induce a rapid and complete inactivation of the K_Ca1.1 channel in a manner that closely resembles the ball-and-chain inactivation of the voltage-dependent K⁺ (K_v) channels. In other words, the inactivation is dependent on a sequence in the N-terminal part of the slob2 subunit that appears to block the mouth of the ion permeation pathway.

The physiological significance of the slob2 subunit is not clear, but it appears to participate in the inactivation of the K_Ca1.1 channel in hippocampal CA1 neurons and adrenal chromaffin cells. 

We are pleased to present a new antibody directed against the intracellular N-terminus of the human slob2. The antibody also recognizes slob2 from rat origin and has been tested for Western and immunohistochemistry applications.