title: Human and rodent MaxiK channel beta-subunit genes: cloning and characterization.
abstract: Voltage- and Ca2+-sensitive K+ (MaxiK) channels play key roles in controlling neuronal excitability and vascular tone. We cloned and analyzed human and rodent genes for the modulatory beta subunit, KCNMB1. The human and mouse beta-subunit genes are approximately 11 and approximately 9 kb in length, respectively, and have a four exon-three intron structure. Primer extension assay localized the transcription initiation site at 442 (human) or 440 (mouse) bp upstream of the translation initiation codon, agreeing with the transcript size in Northern blots. Both genes have a TATA-less putative promoter region, with a transcription initiator-like region, and motifs characteristic of regulated promoters, including muscle-specific enhancing factors-1 and -2. Consistent with a tissue-specific expression of KCNMB1, regulated at the transcriptional level, beta-subunit transcripts are abundant in smooth muscle and heart, but scarce in lymphatic tissues, brain, and liver. Expressed rat and mouse beta subunits increase the apparent Ca2+ sensitivity of the human MaxiK channel alpha subunit.
authors.affiliation: Department of Anesthesiology, University of California at Los Angeles, Los Angeles, California, 90095-1778, USA.
authors.forename: Z
authors.initials: Z
authors.lastname: Jiang
authors.forename: M
authors.initials: M
authors.lastname: Wallner
authors.forename: P
authors.initials: P
authors.lastname: Meera
authors.forename: L
authors.initials: L
authors.lastname: Toro
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D002462:Cell Membrane / Q000737:chemistry; D003001:Cloning, Molecular; D004247:DNA; D005786:Gene Expression Regulation; D006801:Humans; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051038:Large-Conductance Calcium-Activated Potassium Channel beta Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D051379:Mice; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D024681:Potassium Channels, Calcium-Activated; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D051381:Rats; D015183:Restriction Mapping; D017386:Sequence Homology, Amino Acid
chemical_list: C494841:KCNMA1 protein, human; C531905:KCNMB1 protein, human; C494842:Kcnma1 protein, rat; D051037:Large-Conductance Calcium-Activated Potassium Channel alpha Subunits; D051038:Large-Conductance Calcium-Activated Potassium Channel beta Subunits; D051036:Large-Conductance Calcium-Activated Potassium Channels; D015221:Potassium Channels; D024681:Potassium Channels, Calcium-Activated; D004247:DNA