KMID : 0620919970290040217
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Experimental & Molecular Medicine 1997 Volume.29 No. 4 p.217 ~ p.221
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Structure of human voltage-dependent calcium channel (VDCC) ¥â3 subunit gene
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Hyung Lae Kim/Yoon Jeong Chang
Kyung Hea Cho/Yong Sook Hong/Sang Moo Lee/Hyung Lae Kim
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Abstract
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In excitable and endocrine organs, calcium influxes through the voltage-dependent calcium channel (VDCC), composed of four (¥á1, ¥á2, ¥â, and ¥ä) subunits. Four isoforms of ¥â subunits (¥â1, ¥â2, ¥â3, ¥â4) are known to exist, The cytoplasmic ¥â subunits regulate the channel activity by accelerating the kinetics of activation and inactivation through phosphorylation. Regulation of calcium channel activities are also provided by alternative splicing of the ¥â subunits. To elucidate the genomic organization of the VDCC ¥â3 subunit gene, two genomic clones were isolated from human genomic liabrary using the whole rat cDNA for ¥â3 subunit as a probe. The ¥â3 subunit gene in lamda phage DNA was analyzed by Southern hybridization and sequencing. A 19.1 kb clone (2BHG13) contained the whole ¥â3 cDNA sequence, consisting at least 14 exons. The deduced amino acid sequence from the exons shows 97% similarity with that of rat gene. Two alternatively spliced forms of ¥â3 subunit at 5'-end were found. The ¥â3 subunit had many possible phosphorylation sites. Alternative splicing of ¥â3 subunit mRNA at 5'-end and phosphorylation of the ¥â3 subunit protein may play a regulatory role in calcium influxes.
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KEYWORD
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voltage-dependent clacium channel, ¥â3 subunit, alternatively splicng, human genome, exon,
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