CLONING, CHROMOSOMAL LOCATION AND FUNCTIONAL EXPRESSION OF THE HUMAN VOLTAGE-DEPENDENT CALCIUM-CHANNEL BETA-3 SUBUNIT

A novel human-voltage-dependent-calcium-channel (VDCC) beta subunit wa s isolated from a 9-week-old human total-embryo cDNA library. Of the f our genes encoding beta-subunit isoforms that have been identified in animal species, this isoform shares strong similarity with the rat and rabbit beta(3)-related gene product and is referred to here as H beta (3) subunit. The H beta(3) isoform is the second beta subunit identifi ed in human. Its open reading frame encodes a 482-amino-acid protein w ith a predicted molecular mass of 54.571 kDa. The H beta(3) mRNA is ex pressed mostly in brain, smooth muscle and ovary. The gene for the hum an H beta(3) was specifically localized on chromosome 12q13. The clone d H beta(3) subunit was further expressed in Xenopus oocytes to demons trate its ability to modulate VDCC activity.