KCa3.1 - "Modulation of hKCa3.1 by internal Ca2+ performed on Nanion’s Patchliner"
The intermediate-conductance calcium-activated K+ channel, also known as KCa3.1, IKCa1 or SK4, is a member of the large family of potassium channels gated by calcium. It can be distinguished from the other calcium-activated K+ channels by differences in channel conductance, calcium sensitivity, voltage dependence and pharmacological properties. The hKCa3.1 channel is encoded by the KCNN4 gene. It is primarily expressed in peripheral tissues, including those of the hematopoietic system, colon, lung, placenta, and pancreas and has been proposed to play an important role in a variety of physiological processes including volume regulation in erythrocytes, proliferation and differentiation of B- and T-lymphocytes, and tissue protection following spinal cord injury. Importantly, the hKCa3.1 channel is a promising therapeutic target for a variety of health disorders including sickle cell anaemia and immunological disorders. The Ca2+-binding protein, calmodulin (CaM), is required for the activation of hKCa3.1. The Ca2+-CaM complex is proposed to bind to an intracellular domain of the C terminus of all subunits in the tetramer, inducing conformational changes to open the channel. In this study the Patchliner was used to perform a biophysical and pharmacological characterization of hKCa3.1 channels expressed in CHO cells. hKCa3.1 was activated by exchanging the internal solution to a solution containing free-Ca2+ and blocked by external application of non-selective (BaCl2) and selective (TRAM-34) inhibitors with an IC50 value consistent with that reported in the literature.