Chromosomal Localization and Neural Distribution of Voltage Dependent Calcium Channel β₃ Subunit Gene

Voltage dependent calcium channel (VDCC) mediates the influx of free calcium ions that acts as a signal transducer. The beta 3 subunit of the VDCC regulates the activation (opening) and inactivation (closing) kinetics through phosphorylation/dephosphorylation. We isolated a genomic clone of the human VDCC β₃ subunit from a human genomic DNA library using VDCC β₃ cDNA as a probe. We localized VDCC β₃ with this genomic DNA on the chromosome by fluorescent in situ hybridization, and the distribution of VDCC β₃ in the nervous system was investigated in rats by in situ hybridization histochemistry with rat VDCC β₃ cDNA. The gene for the VDCC β₃ was specifically localized on human chromosome 12q13. The mRNA for the VDCC β₃ was predominently expressed in the nervous system. In the brain, a strong expression of VDCC β₃ mRNA was found in the medial habenular nucleus, a high level of expression was observed in the olfactory bulb and cerebellum, and a relatively high level of VDCC β₃ mRNA was localized in the cerebral cortex, caudate-putamen and hippocampal formation. Interestingly, this distribution pattern is very similar to that of the rbE-II, mid-low VDCC 1 subunit, and it is suspected that VDCC β₃ and rbE-II may function together as a pair.