sr-(Octapeptide-7 Hexapeptide-128) is a single chain fusion peptide, produced by fermentation in E. coli. The starting gene is synthesized by the fusion of the gene from Octapeptide-7 and Hexapeptide-128. The fusion peptide contains 13 amino acids which may contain disulfide bonds and/or glycosylation, and consists of the proper sequence of the 20 standard amino acids.