KCNMB4

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. [provided by RefSeq, Jul 2008]

Potassium Calcium-Activated Channel Subfamily M Regulatory Beta Subunit 4

Regulatory subunit of the calcium activated potassium KCNMA1 (maxiK) channel. Modulates the calcium sensitivity and gating kinetics of KCNMA1, thereby contributing to KCNMA1 channel diversity. Decreases the gating kinetics and calcium sensitivity of the KCNMA1 channel, but with fast deactivation kinetics. May decrease KCNMA1 channel openings at low calcium concentrations but increases channel openings at high calcium concentrations. Makes KCNMA1 channel resistant to 100 nM charybdotoxin (CTX) toxin concentrations.

Action potentialManual Assertion Based On ExperimentIDA:UniProtKB
Chemical synaptic transmissionManual Assertion Based On ExperimentTAS:ProtInc
Detection of calcium ionManual Assertion Based On ExperimentIDA:UniProtKB
Neuronal action potentialManual Assertion Based On ExperimentIDA:UniProtKB
Potassium ion transportManual Assertion Based On ExperimentIDA:UniProtKB
Regulation of neurotransmitter secretionManual Assertion Based On ExperimentTAS:UniProtKB
Regulation of vasoconstrictionManual Assertion Based On ExperimentTAS:UniProtKB

Membrane

Cytoplasmic: 1-19
Helical: 20-40
Extracellular: 41-167
Helical: 168-188
Cytoplasmic: 189-210

Phosphorylated. Phosphorylation modulates its effect on KCNMA1 activation kinetics.
N-glycosylated. A highly glycosylated form is promoted by KCNMA1. Glycosylation, which is not required for the interaction with KCNMA1 and subcellular location, increases protection against charybdotoxin.