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 product of this gene, the modulatory beta subunit. Intracellular calcium regulates the physical association between the alpha and beta subunits. [provided by RefSeq, Jul 2008]
Function:
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. Increases the apparent Ca2+/voltage sensitivity of the KCNMA1 channel. It also modifies KCNMA1 channel kinetics and alters its pharmacological properties. It slows down the activation and the deactivation kinetics of the channel. Acts as a negative regulator of smooth muscle contraction by enhancing the calcium sensitivity to KCNMA1. Its presence is also a requirement for internal binding of the KCNMA1 channel opener dehydrosoyasaponin I (DHS-1) triterpene glycoside and for external binding of the agonist hormone 17-beta-estradiol (E2). Increases the binding activity of charybdotoxin (CTX) toxin to KCNMA1 peptide blocker by increasing the CTX association rate and decreasing the dissociation rate.
Subunit:
Interacts with KCNMA1 tetramer. There are probably 4 molecules of KCMNB1 per KCNMA1 tetramer.
Subcellular Location:
Membrane; Multi-pass membrane protein.
Tissue Specificity:
Abundantly expressed in smooth muscle. Low levels of expression in most other tissues. Within the brain, relatively high levels found in hippocampus and corpus callosum.
Post-translational modifications:
N-glycosylated.
Similarity:
Belongs to the KCNMB (TC 8.A.14.1) family. KCNMB1 subfamily. [View classification]
SWISS:
Q16558
Gene ID:
3779
Database links:
Entrez Gene: 3779 Human
Entrez Gene: 16533 Mouse
Entrez Gene: 100009034 Rabbit
Entrez Gene: 29747 Rat
Omim: 603951 Human
SwissProt: Q16558 Human
SwissProt: Q8CAE3 Mouse
SwissProt: O46372 Rabbit
SwissProt: P97678 Rat
Unigene: 416899 Human
Unigene: 10820 Rat
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