Hysteretic behavior of the hepatic microsomal glucose-6-phosphatase system.
Biochim Biophys Acta
; 1118(1): 91-8, 1991 Dec 11.
Article
en En
| MEDLINE
| ID: mdl-1662542
ABSTRACT
Carbamyl-Pglucose and PPiglucose phosphotransferase, but not inorganic pyrophosphatase, activities of the hepatic microsomal glucose-6-phosphatase system demonstrate a time-dependent lag in product production with 1 mM phosphate substrate. Glucose-6-P phosphohydrolase shows a similar behavior with [glucose-6-P] less than or equal to 0.10 mM, but inorganic pyrophosphatase activity does not even at the 0.05 or 0.02 mM level. The hysteretic behavior is abolished when the structural integrity of the microsomes is destroyed by detergent treatment. Calculations indicate that an intramicrosomal glucose-6-P concentration of between 20 and 40 microM must be achieved, whether in response to exogenously added glucose-6-P or via intramicrosomal synthesis by carbamyl-Pglucose or PPiglucose phosphotransferase activity, before the maximally active form of the enzyme system is achieved. It is suggested that translocase T1, the transport component of the glucose-6-phosphatase system specific for glucose-6-P, is the target for activation by these critical intramicrosomal concentrations of glucose-6-P.
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Banco de datos:
MEDLINE
Asunto principal:
Microsomas Hepáticos
/
Glucofosfatos
Límite:
Animals
Idioma:
En
Año:
1991
Tipo del documento:
Article