Referenced in: none

Automatically associated channels: Kir2.3

Title: Mutually exclusive exon splicing of the cardiac calcium channel alpha 1 subunit gene generates developmentally regulated isoforms in the rat heart.

Authors: R J Diebold, W J Koch, P T Ellinor, J J Wang, M Muthuchamy, D F Wieczorek, A Schwartz

Journal, date & volume: Proc. Natl. Acad. Sci. U.S.A., 1992 Feb 15 , 89, 1497-501

PubMed link: http://www.ncbi.nlm.nih.gov/pubmed/1311102

Abstract
Several clones were isolated from a rat genomic library in order to further characterize a region of variability within the third membrane-spanning region of the fourth motif (IVS3) of the L-type voltage-dependent calcium channel. We report here that this diversity arises from alternative splicing of a primary transcript containing a single pair of adjacent exons each encoding a unique sequence for the IVS3 region. Definitive proof of a mutually exclusive splicing mechanism was obtained by genomic mapping of flanking upstream and downstream exons and by extensive sequence analysis of the relevant exon/intron boundaries. S1 nuclease protection experiments revealed that both variant forms of the IVS3 were equally expressed in newborn and fetal rat heart, whereas only a single isoform predominated in adult rat heart. The results demonstrate the existence of an important developmentally regulated switch mediated by alternatively spliced exons in cardiac tissue at a time when major changes in excitation occur.