cDNA sequence analysis of cardiotoxin variants from Taiwan cobra.

Five cDNAs encoding cardiotoxin variants were constructed from the cellular RNA isolated from the venom glands of Naja naja atra by reverse transcription-polymerase chain reaction. A high degree of nucleotide sequence homology was observed between these variants and other determined ones. Among them, a novel cardiotoxin 6 had 61 amino acid residues rather than 60 ones that usually observed with Naja naja atra cardiotoxins. The other cardiotoxin variants were the homologues of cardiotoxins 1, V or N with one or two amino acid substitutions, respectively. These results probably reflect the involvement of RNA editing in the production of cardiotoxin variants in the venom of Taiwan cobra.