Discrimination of transport systems of L-tyrosine in mouse mammary gland: characterization of system T.
Indian J Exp Biol
;
1996 Aug; 34(8): 750-7
Artigo
em Inglês
| IMSEAR
| ID: sea-63329
ABSTRACT
On the basis of inhibition analysis, tyrosine uptake in mouse mammary gland was found to be mediated by Na(+)-dependent and Na(+)-independent systems. Na(+)-dependent system was insensitive to 2-(methylamino) isobutyric acid (MeAIB), with an apparent Km of 1.67 mM and maximal velocity 74.5 nmol.g-1 cell. min-1. Competition experiments showed the presence of two distinct Na(+)-independent components of tyrosine uptake. One component was sensitive to 2-aminobicyclo (2,2,1) heptane-2-carboxylic acid (BCH) and was similar to the system L, with an apparent Km of 0.23 mM and maximum velocity of 31 nmol.g-1 cell.min-1. Second component was BCH-insensitive but tryptophan-sensitive, with an apparent Km of 15.75 mM and Vmax of 157.5 nmol.g-1cell.min-1. BCH-insensitive, tryptophan-sensitive system was a low affinity system. It approached steady state slowly and was more sensitive, relative to the system L, to n-ethylmaleimide inhibition. Tyrosine uptake through this system did not respond to trans-stimulation, whereas system L mediated uptake responded considerably. BCH-insensitive, tryptophan-sensitive component of Na(+)-independent tyrosine uptake is attributed to the system T, previously described only in human red blood cells and rat liver cells.
Texto completo:
DisponíveL
Índice:
IMSEAR (Sudeste Asiático)
Assunto principal:
Sódio
/
Estereoisomerismo
/
Tirosina
/
Transporte Biológico
/
Feminino
/
Animais
/
Glândulas Mamárias Animais
/
Camundongos
Tipo de estudo:
Estudo prognóstico
Idioma:
Inglês
Revista:
Indian J Exp Biol
Ano de publicação:
1996
Tipo de documento:
Artigo
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