sr-Cone Snail Mu-Conotoxin TIIIA is a single chain protein produced by fermentation in E. coli. The starting gene is a synthetically produced to be identical to Mu-conotoxin TIIIA which is found in the cone snail, Conus. The protein contains 22 amino acids which may contain disulfide bonds and/or glycosylation, and consists of the proper sequence of the 20 standard amino acids.