cDNA cloning and sequence analysis of six neurotoxin-like proteins from Chinese continental banded krait.

The cDNAs encoding six neurotoxin-like proteins were cloned from the total RNA isolated from one venom gland of Bungarus multicinctus multicinctus by reverse transcription-polymerase chain reaction. Although they shared a high degree of nucleotide sequence homology, the deduced proteins displayed a rather low extent of identical residues with the exception that the 21 residue signal peptides were highly conserved. Each mature protein consisted of 65, 66 or 68 amino acids with four or five disulfide bonds respectively. Comparative sequence analyses showed that they were structurally related to neurotoxin homologues. Phylogenetic analyses implied that they might represent two different evolutionary branches.