Calcium-activated potassium channel subunit beta-4 is a protein that in humans is encoded by the KCNMB4gene.
MaxiK channels are large conductance, voltage and calcium-sensitive potassium channels which are fundamental to the control of smooth muscle tone and neuronal excitability. MaxiK channels can be formed by 2 subunits: the pore-forming alpha subunit and the modulatory beta subunit. The protein encoded by this gene is an auxiliary beta subunit which slows activation kinetics, leads to steeper calcium sensitivity, and shifts the voltage range of current activation to more negative potentials than does the beta 1 subunit.
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↑Behrens R, Nolting A, Reimann F, Schwarz M, Waldschutz R, Pongs O (Jul 2000). "hKCNMB3 and hKCNMB4, cloning and characterization of two members of the large-conductance calcium-activated potassium channel beta subunit family". FEBS Lett. 474 (1): 99–106. doi:10.1016/S0014-5793(00)01584-2. PMID10828459.
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Jin P, Weiger TM, Wu Y, Levitan IB (2002). "Phosphorylation-dependent functional coupling of hSlo calcium-dependent potassium channel and its hbeta 4 subunit". J. Biol. Chem. 277 (12): 10014–20. doi:10.1074/jbc.M107682200. PMID11790768.
Jin P, Weiger TM, Levitan IB (2003). "Reciprocal modulation between the alpha and beta 4 subunits of hSlo calcium-dependent potassium channels". J. Biol. Chem. 277 (46): 43724–9. doi:10.1074/jbc.M205795200. PMID12223479.