Opossum insulin, glucagon and pancreatic polypeptide: amino acid sequences.

Pancreatic hormones have been purified from the opossum, a New World marsupial. Opossum insulin contains a Leu substitution at the N-terminus of the B-chain in place of the Phe that is generally present in mammalian insulins. In addition, there are two other amino acid substitutions in the opossum insulin A-chain (positions 8 and 18) compared to pig insulin. Opossum glucagon is identical to chicken glucagon with both differing from the usual mammalian glucagon by Ser in place of Asn at its penultimate C-terminal position. Opossum PP differs from the porcine peptide in only 3 sites (position 3, 19 and 30).