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. Author manuscript; available in PMC: 2012 May 8.
Published in final edited form as: Expert Rev Clin Pharmacol. 2010 May;3(3):385–396. doi: 10.1586/ecp.10.11

Figure 1.

Figure 1

Properties of KCa3.1 channels. A. Simplified phylogenetic tree of genes for human potassium channel subunits, highlighting in red the two gene families that comprise Ca2+-activated potassium channels and further highlighting the KCNN family which contains the gene for KCa3.1 (KCNN4). B. Illustration of KCa3.1 subunit topology showing the six transmembrane domain signature of this class of channels, along with calmodulin attached to a calmodulin binding domain on the C terminus. The location of the histidine phosphorylation site (H358) known to affect channel activation is also shown. C. Illustration of the homo-tetrameric nature of functional KCa3.1 channels, showing the presence of four calmodulin calcium sensors which accounts for the channel’s steep, highly cooperative sensitivity to changes in intracellular calcium concentration.