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Biochim Biophys Acta. 1999 Jan 4;1436(3):541-9.

Short-term regulation of carnitine palmitoyltransferase I in cultured rat hepatocytes: spontaneous inactivation and reactivation by fatty acids.

Author information

1
Institute of Medical Biochemistry, University of Oslo, Norway. jowita@basalmed.uio.no

Abstract

Liver carnitine palmitoyltransferase I (CPT I), the rate-limiting enzyme of mitochondrial beta-oxidation, rapidly loses its activity when hepatocytes are put in culture. 3-Thia fatty acids reactivate the enzyme and can increase its activity 3-4-fold in 5-10 min. Normal fatty acids are also able to stimulate CPT I, but to a limited extent, compared to 3-thia fatty acid. This activation does not affect malonyl-CoA sensitivity. CPT I in hepatocytes from both fasted and fasted-carbohydrate refed rats is inactivated and reactivated to a similar extent. Free dodecylthioacetic acid (DTA) is at least as efficient as DTA-CoA as activator. CPT I activity in isolated mitochondria is not influenced by incubation with DTA, suggesting that the regulation of CPT I depends on an extramitochondrial component(s) in the cell. It is concluded that fatty acids activate pre-existing, inactive CPT I without involvement of gene transcription and independently of malonyl-CoA.

PMID:
9989283
DOI:
10.1016/s0005-2760(98)00164-7
[Indexed for MEDLINE]

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