Humatrope (somatropin, rDNA origin, for injection) is a polypeptide hormone of recombinant DNA origin. Humatrope (somatropin rdna origin) is synthesized in a strain of Escherichia coli that has been modified by the addition of the gene for human GH. The peptide is comprised of 191 amino acid residues and has a molecular weight of about 22,125 daltons. The amino acid sequence of the peptide is identical to that of human GH of pituitary origin.