Structure and organization of the cardiotoxin genes in Naja naja sputatrix.
We report the genomic structure, organization and the presence of multiple isoforms of the gene encoding cardiotoxins (CTX) of Naja naja sputatrix. The cardiotoxin gene consists of six CTX isoforms, each (2.2 kb) having three exons and two introns. Two possible transcription initiation sites as well as consensus TATA boxes and transcription factor binding motifs, AP-2, NFIL-6/C/EBP, NF-kappaB and PuF have been identified in the 5'-region of the gene. The CTX gene isoforms show nucleotide variations at specific segments in exon 2 and exon 3, which correspond to the functional domains in the three-finger loop structure of the cardiotoxin molecule. The diverse functions of cardiotoxins together with our findings suggest that the cardiotoxin gene isoforms may have evolved under adaptive pressure through a positive Darwinian selection process.
Lachumanan
R
R
Department of Biochemistry, Faculty of Medicine, National University of Singapore, Singapore.
Armugam
A
A
Tan
C H
CH
Jeyaseelan
K
K
D000595:Amino Acid Sequence; D001483:Base Sequence; D001665:Binding Sites; D015139:Blotting, Southern; D004179:Cobra Cardiotoxin Proteins / Q000235:genetics*; D016384:Consensus Sequence; D004247:DNA / Q000737:chemistry* / Q000378:metabolism; D004546:Elapid Venoms / Q000737:chemistry*; D005091:Exons; D007438:Introns; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D017422:Sequence Analysis, DNA; D016385:TATA Box; D014157:Transcription Factors / Q000378:metabolism
D004179:Cobra Cardiotoxin Proteins; D004546:Elapid Venoms; D014157:Transcription Factors; D004247:DNA