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Regulation of phosphatidic acid phosphohydrolase 1 by fatty acids

Lookup NU author(s): Professor Chris Day, Dr Richard Virden, Emeritus Professor Steve Yeaman

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Abstract

In the starved state and during metabolic stress, free fatty acids (FFA) are the principal hepatic energy supply, undergoing beta-oxidation. Accordingly, it appears paradoxical that FFA have been reported to increase the liver's esterification capacity by translocating the rate-limiting enzyme phosphatidic acid phosphohydrolase (PAP-1) from the cytosol to the endoplasmic reticulum. We have therefore investigated the regulation of rat liver PAP-1. Oleic acid inhibited PAP activity in all subcellular fractions, with PAP-1 activity in cytosol being the most sensitive. Inhibition was also observed with oleoyl-CoA, linoleate, and palmitate. Fatty acids and their derivatives show detergent effects at high concentrations, and such effects can lead to enzyme inhibition. Inhibition by oleate, however, was reversed by phosphatidic acid and albumin and exhibited sigmoidal kinetics. These results demonstrate that PAP-1 is reversibly inhibited by FFA and their CoA esters, which may play a role in directing hepatic FFA to beta-oxidation during times of increased energy demand.

Publication metadata

Author(s): Elabbadi N, Day CP, Virden R, Yeaman SJ

Publication type: Article

Publication status: Published

Journal: Lipids

Year: 2002

Volume: 37

Issue: 1

Pages: 69-73

ISSN (print): 0024-4201

ISSN (electronic): 1558-9307

Publisher: Springer

URL: http://dx.doi.org/10.1007/s11745-002-0865-7

DOI: 10.1007/s11745-002-0865-7

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