The amino acid code of proteins in the small basic polypeptide myotoxin family, which includes crotamine, have been sequenced. They were found to be similar with an average of 83% divergence. A crotamine amino acid sequence was compared to that of cloned DNA of myotoxin a, (the myotoxin used to model how SBPMs work). In the comparison, exon coding regions including the mature myotoxin and the signal peptide were 98% and 100% similar, respectively. The untranslated regions for 5’ and 3’ between the sample and the myotoxin a cDNA was 60% and 80%, respectively. When comparing the amino acid sequences of other proteins not in the SBPM family found in snake venoms, there is usually large divergence. When looking at the SBPM proteins, they have high similarity between different subspecies of the Crotalus genus and between different individuals of the same subspecies. This indicates, according to the Radis-Batista et al. 2003 study, that the crotamine gene and other SBPM genes have evolved recently.