CKβ8 is an alternative splicing form of CKβ8-1. (A) Two BAC clones (110-F-6 and 125-F-14) representing the CKβ8-1 gene were isolated and further analyzed for determination of exon and intron organization of the gene. A 3.0-kb Hind III fragment was isolated from 110F-6 and the entire nucleotide sequence covering a portion of exons 2, 3, and 4 and introns 2 and 3 was determined. A 1.3-kb HindIII fragment was also isolated from 125-F-14 and the entire nucleotide sequence was determined. This sequence included portions of exon 2 and intron 1. Two independent cDNA clones representing CKβ8-1 and CKβ8 were isolated from THP.1 cDNA library. Their sequences were determined. Exons are shown in boxes. The putative splicing donor (gt) or acceptor (cag or tag) consensus sequences are also shown. The Cys-Cys motifs are represented in circles in exon 3, whereas the extra two cysteines are denoted by stars (*) in cDNAs. (B) Alternative splicing deleted 57 bp from exon 3 in CKβ8-1 in such a way that CKβ8 was formed. A 17–amino acid deletion point is indicated in CKβ8 cDNA.