Fiber‐FISH Analysis of the 3'‐Terminal Region of the Human L‐Type Ca2+ Channel α1C Subunit gene

摘要

Human L-type Ca2+ channel α1C subunit gene (CACNL1A1) maps to the distal region of chromosome 12p13. and is composed of ≈ 50 exons spanning over 150 kb of the human genome as estimated by restriction map analysis. However, the structure and the total length of the 3'-end of the gene is not clear because the size of several big introns remains unknown. Here the fiber-FISH technique was used to determine the relative order and size of eight partial genomic DNA clones from the central and 3'-terminal regions of CACNL1A1. The total physical distance of this region, including the size and gap distances between the clones were re-estimated. The results show that the physical order of the tested clones was 5'- g14-5 g12-2 g10-8 g4-5 g16-7 g8-3 g12-5 g6-20 -3‘. Their individual sizes vary between 6.7 and 21.9 kb. Clones g6-20 and g12-5, both containing repetitive exon 45/46-like element, were found to be located within 59.1 kb downstream of g8-3 containing earlier identified polyadenylation site, i.e. 229.5 kb away from clone g14-5 (exons 10, 11). The possible implications of this structural complexity is discussed.