Fig. 1. Generation of α1GT-type calcium channel knockout mice by a Cre/loxP recombination system. ( A ) Schematic representation of α1GT-type calcium channel complementary DNA (cDNA), α1G+allele (α1G+), targeting vector (Vector), targeted α1Gloxallele (α1Glox), and α1G−allele (α1G−) after Cre-mediated recombination. Black areas of cDNA represent the nucleotide sequences encoding the membrane spanning segments S1–S6 of repeat I of the α1Gchannel. White boxes represent exon sequences, Pgk-1 promoter-neo-pA cassette (neo), and diphtheria toxin cassette (DT). LoxP and frt sites are shown by black triangles and white half-circles , respectively. Gray boxes indicate probe regions (neo and 3′) used for Southern blot analysis. K is the Kpn I site. ( B ) Southern blot analysis of genomic DNA from α1G+/+, α1Glox/lox, and α1G−/−mice. Left : Kpn I -digested DNA hybridized with a neo probe. Right : Kpn I-digested DNA hybridized with a 3′ probe. The black triangle indicates the 14.7-kb fragment from the α1G−allele. The white triangle indicates the 5.9-kb fragment from the α1G+allele. The triangle with a black upper half indicates the 17.2-kb fragment from the α1Gloxallele.