Ontogeny of two topologically distinct TRH-degrading pyroglutamate aminopeptidase activities in the rat liver.
We recently separated and characterized two topologically distinct pyroglutamate aminopeptidase (PAP) activities in adult rat liver, which convert TRH to cyclo His-Pro (cHP). The liver possesses high-affinity binding sites to the biologically active dipeptide cHP and is thus a potential target tissue for pancreatic TRH and/or its conversion product cHP, and may be a site of TRH conversion and/or inactivation. This report describes the ontogenic development of two liver PAP activities and compares them with that of plasma thyroliberinase. The particulate high-molecular-weight PAP was absent at birth and during the neonatal period, while the soluble, low-molecular-weight PAP was present at all the developmental stages tested. The changes in particulate PAP activity are similar to those in the plasma of age-matched rats. The peculiar age-dependent changes in particulate PAP activity, plus its cellular location, suggest that it has a regulatory role.
INSERM U.30, Hôpital des Enfants Malades, Paris, France.
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Scharfmann
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Aratan-Spire
D000375:Aging; D000626:Aminopeptidases; D000818:Animals; D002850:Chromatography, Gel; D006868:Hydrolysis; D008099:Liver / Q000196:embryology* / Q000201:enzymology; D008297:Male; D011751:Pyroglutamyl-Peptidase I / Q000378:metabolism*; D011761:Pyrrolidonecarboxylic Acid / Q000031:analogs & derivatives; D051381:Rats; D011919:Rats, Inbred Strains; D012697:Serine Endopeptidases / Q000097:blood; D012995:Solubility; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism
D013973:Thyrotropin-Releasing Hormone; D000626:Aminopeptidases; D011751:Pyroglutamyl-Peptidase I; C023166:pyroglutamyl-peptidase II; D012697:Serine Endopeptidases; D011761:Pyrrolidonecarboxylic Acid