Isolation and characterization of the 5'-upstream region of the human N-type calcium channel alpha1B subunit gene. Chromosomal localization and promoter analysis.
omega-Conotoxin-sensitive N-type Ca2+ channels, unlike dihydropyridine-sensitive L-type channels, are exclusively expressed in nervous tissues. To understand the molecular basis for neuron-specific expression of the N-type channel, we have isolated genomic clones encoding the human alpha1B subunit gene, localized to the long arm of chromosome 9 (9q34) by fluorescence in situ hybridization, and characterized its 5'-upstream region. The proximal promoter of the alpha1B subunit gene lacks a typical TATA box, is highly GC-rich, and contains several sequences for transcription factor binding. Primer extension experiments revealed the presence of two transcription start sites. In vitro transfection study of the alpha1B subunit-luciferase fusion gene showed that the 4.0-kb 5'-flanking region of the alpha1B gene functions as an efficient promoter in neuronal cells but not in glioma or nonneuronal cells, consistent with the patterns of the endogenous alpha1B gene expression in these cells. Deletion analysis of alpha1B subunit-luciferase fusion gene constructs further revealed the presence of several cis-acting regulatory elements, including a potential repressor located in the distal upstream region (-3992 to -1788) that may be important for the neuron-specific expression of the N-type Ca2+ channel alpha1B subunit gene.
Kim
D S
DS
Laboratory of Neurochemistry, NINDS, National Institutes of Health, Bethesda, Maryland 20892, USA.
Jung
H H
HH
Park
S H
SH
Chin
H
H
D000595:Amino Acid Sequence; D001483:Base Sequence; D015220:Calcium Channels / Q000235:genetics*; D002874:Chromosome Mapping; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics*; D017422:Sequence Analysis, DNA
D015220:Calcium Channels