peptide hormone glucagon A 29-amino acid peptide hormone consisting of His, Ser, Gln, Gly, Thr, Phe, Thr, Ser, Asp, Tyr, Ser, Lys, Tyr, Leu, Asp, Ser, Arg, Arg, Ala, Gln, Asp, Phe, Val, Gln, Trp, Leu, Met, Asn and Thr residues joined in sequence.