0142484 - FGU-C 20030100 RIV US eng J - Článek v odborném periodiku
Žáčková, Markéta - Škobisová, Eva - Urbánková, Eva - Ježek, Petr
Activating omega-6 polyunsaturated fatty acids and inhibitory purine nucleotides are high affinity ligands for novel mitochondrial uncoupling proteins UCP2 and UCP3.
Journal of Biological Chemistry. Roč. 278, č. 23 (2003), s. 20761-20769. ISSN 0021-9258. E-ISSN 1083-351X
Grant CEP: GA AV ČR IAA5011106; GA ČR GA301/02/1215; GA MŠMT ME 389
Výzkumný záměr: CEZ:AV0Z5011922
Klíčová slova: uncoupling protein-2 * polyunsaturated fatty acids * recombinant yeast expression
Kód oboru RIV: CE - Biochemie
Impakt faktor: 6.482, rok: 2003

Human UCP2 and UCP3, expressed in yeast, were studied to establish their high affinity regulatory ligands. UCPn were reconstituted into liposomes and assayed for fatty acid (FA)-induced H+ efflux. All natural long chain FAs activated UCP2- and UCP3-mediated H+ translocation. Coenzyme Q10 had no further significant activating effect. Evaluated parameters of FA activation (FA cycling) kinetics revealed the highest apparent affinity to UCP2 for omega-6 polyunsaturated FAs (PUFAs), all-cis-8,11,14-eicosatrienoic and all-cis-6,9,12-octadecatrienoic acids, which are also the most potent agonists of the nuclear PPAR-beta receptor in the activation of UCP2 transcription. Omega-3 PUFA, cis-5,8,11,14,17-eicosapentaenoic acid had lower affinity. Although being omega-6 PUFA, arachidonic acid exhibited the same low affinity as lauric acid. These findings suggest a possible dual role of some PUFAs in activating both, UCPn expression and uncoupling activity. UCP2(UCP3)-dependent H+ translocation activated by all tested FAs was inhibited by purine nucleotides with apparent affinity to UCP2 (reciprocal Ki) decreasing in order: ADP > ATP ~ GTP > GDP >> AMP. Also 3H-GTP (3H-ATP) binding to isolated E.coli or yeast-expressed UCP2 or UCP3 exhibited high affinity, similar to UCP1. The estimated number of 3H-GTP high affinity binding sites was (in pmols/mg protein) 182 in lung mitochondria; 74 in kidney; 28 in skeletal muscle; and ~20 in liver mitochondria. We conclude that purine nucleotides must be the physiological inhibitors of the UCPn-mediated uncoupling in vivo.
Trvalý link: http://hdl.handle.net/11104/0040187