Mammalian forebrain ketimine reductase identified as µ-crystallin; potential regulation by thyroid hormones.
J Neurochem
; 118(3): 379-87, 2011 Aug.
Article
en En
| MEDLINE
| ID: mdl-21332720
Ketimine reductase (E.C. 1.5.1.25) was purified to apparent homogeneity from lamb forebrain by means of a rapid multi-step chromatography protocol. The purified enzyme was identified by MS/MS (mass spectrometry) as µ-crystallin. The identity was confirmed by heterologously expressing human µ-crystallin in Escherichia coli and subsequent chromatographic purification of the protein. The purified human µ-crystallin was confirmed to have ketimine reductase activity with a maximum specific activity similar to that of native ovine ketimine reductase, and was found to catalyse a sequential reaction. The enzyme substrates are putative neuromodulator/transmitters. The thyroid hormone 3,5,3'-l-triiodothyronine (T3) was found to be a strong reversible competitive inhibitor, and may have a novel role in regulating their concentrations. µ-Crystallin is also involved in intracellular T3 storage and transport. This research is the first to demonstrate an enzyme function for µ-crystallin. This newly demonstrated enzymatic activity identifies a new role for thyroid hormones in regulating mammalian amino acid metabolism, and a possible reciprocal role of enzyme activity regulating bioavailability of intracellular T3.
Texto completo:
1
Colección:
01-internacional
Base de datos:
MEDLINE
Asunto principal:
Hormonas Tiroideas
/
Prosencéfalo
/
Cristalinas
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Oxidorreductasas actuantes sobre Donantes de Grupo CH-NH
Límite:
Animals
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Humans
Idioma:
En
Revista:
J Neurochem
Año:
2011
Tipo del documento:
Article
País de afiliación:
Australia
Pais de publicación:
Reino Unido