Korean J Anat.  1998 Apr;31(2):253-261.

Cloning and localization of two forms of voltage-dependent calcium channel beta3 subunit gene

• Kim HL
• Kim H
• Park SH
• Kim DY
• Suh YS

Abstract

Voltage-dependent calcium channel (VDCC) is composed of at least four subunits: alpha1, alpha2, beta, delta. Four mammalian beta subunit isoforms (beta1, beta2, beta3 and beta4) have been identified from nervous system. beta subunit accelerates the kinetics of activation (channel openning) and inactivation (channel closure), and regulates the channel activity by phosphorylation through various signal transduction mechanisms. We have cloned three cDNAs (RB8, RB10, and RB11) encoding beta3 subunit of voltage-dependent calcium channel from rat cDNA library using the oligonucleotides of which sequences obtained from the highly conserved regions of rat b subunits. The RB8 and RB10 (rtB3a) encode a same protein of 484 amino acids with estimated Mr of 54,571 Da, which was identical to beta3 subunit gene previously reported. The RB11 (rtbBb) is diffferent from RB10 at N-terminal region but shares common amino acid sequences from the glycine, the 16th amino acid of RB10, to the end of the gene. Open reading frame of RB10 encodes a 483 amino-acid protein with a predicted Mr of 54,473 Da. The RB10 and RB11 are suspected to be alternatively spliced variants from a single b3 subunit gene. The existence of the variants was confirmed by RT-PCR using the oligonucleotide primers from the specific sequences of each variant. The expression patterns of VDCC beta3 (rtB3a) and its specific variant (rtB3b) were investigated in the rat brain by in situ hybridization histochemistry. The mRNAs for rtB3a and rtB3b were exclusively expressed in the nervous system. In the brain, strong expression of both mRNAs (rtB3a and rtB3b) was found in the medial habenular nucleus of thalamus, hippocampus, dentate gyrus, olfactory bulb and cerebellum. But significant discrepancy of expression was found in the lateral posterior thalamic nucleus and olfactory bulb. From these results, it is suspected that newly cloned VDCC variant (rtB3b) should be the alternatively spliced variant of VDCC beta3 gene.

Keyword

voltage-dependent calcium channel; alternative splicing; in situ hybridization histochemistry

MeSH Terms

Alternative Splicing
Amino Acid Sequence
Amino Acids
Animals
Brain
Calcium Channels*
Calcium*
Cerebellum
Clone Cells*
Cloning, Organism*
Dentate Gyrus
DNA Primers
DNA, Complementary
Gene Library
Glycine
Habenula
Hippocampus
In Situ Hybridization
Kinetics
Lateral Thalamic Nuclei
Nervous System
Olfactory Bulb
Oligonucleotides
Open Reading Frames
Phosphorylation
Protein Isoforms
Rats
RNA, Messenger
Signal Transduction
Thalamus
Amino Acids
Calcium
Calcium Channels
DNA Primers
DNA, Complementary
Glycine
Oligonucleotides
Protein Isoforms
RNA, Messenger