title: Metabolism of proctolin, a pentapeptide neurotransmitter in insects.
abstract: The in vitro metabolism of [tyrosyl-3, 5-3H]proctolin (H-Arg-Tyr-Leu-Pro-Thr-OH) was studied in the following tissues from the American cockroach, Periplaneta americana: proctodeum, midgut, hemolymph, brain, terminal ganglion, and coxal depressor muscles. In all tissues assayed, the Tyr-Leu bond is the primary cleavage site, but scission of the Arg-Tyr bond is also significant. Greater than 90% of the degradative activity is found in the 100,000 X g supernatant from homogenates. In vivo studies with the tobacco hornworm, Manduca sexta, show that topically applied proctolin does not penetrate larval cuticle; proctolin is readily degraded to constituent amino acids (at least to Tyr) upon ingestion.
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism; D002853:Chromatography, Liquid; D003058:Cockroaches; D006458:Hemolymph / Q000378:metabolism; D007313:Insecta; D008297:Male; D009132:Muscles / Q000378:metabolism; D009479:Neuropeptides; D018377:Neurotransmitter Agents / Q000378:metabolism*; D009842:Oligopeptides / Q000378:metabolism*
chemical_list: D009479:Neuropeptides; D018377:Neurotransmitter Agents; D009842:Oligopeptides; C011536:proctolin