Tight binding of deoxyribonucleotide triphosphates to human thymidine kinase 2 expressed in Escherichia coli. Purification and partial characterization of its dimeric and tetrameric forms.

Human thymidine kinase 2 (hTK2) phosphorylates pyrimidine deoxyribonucleosides to the corresponding nucleoside monophosphates, using a nucleotide triphosphate as a phosphate donor. In this study, hTK2 was cloned and expressed at high levels in Escherichia coli as a fusion protein with maltose-binding protein. Induction of a heat-shock response by ethanol and coexpression of plasmid-encoded GroEL/ES chaperonins at 28 degrees C minimized the nonspecific aggregation of the hybrid protein and improved the recovery of three homooligomeric forms of the properly folded enzyme, i.

Retinoic acid is a high affinity selective ligand for the peroxisome proliferator-activated receptor beta/delta.

Retinoic acid (RA) modulates transcription of numerous target genes, thereby regulating a myriad of biological processes. It is well established that RA functions by activating retinoic acid receptors (RARs), which, in turn, control cell differentiation, proliferation, and apoptosis. However, perplexing reports of diverse and sometime opposing actions of RA have been published.

Transient up-regulation of liver mitochondrial thymidine kinase activity in proliferating mitochondria.

Administration of the fatty acid analogue tetradecylthioacetic acid (TTA) to rodents up-regulates peroxisomal and mitochondrial lipid-metabolizing enzymes and induces a proliferation of these organelles in hepatocytes. We show here that male NMRI mice fed a diet containing 0.3% (w/w) TTA revealed a transient two-fold increase in the incorporation of [3H]thymidine into the liver mtDNA followed by a 1.

Acyl-CoA esters antagonize the effects of ligands on peroxisome proliferator-activated receptor alpha conformation, DNA binding, and interaction with Co-factors.

The peroxisome proliferator-activated receptor alpha (PPARalpha) is a ligand-activated transcription factor and a key regulator of lipid homeostasis. Numerous fatty acids and eicosanoids serve as ligands and activators for PPARalpha. Here we demonstrate that S-hexadecyl-CoA, a nonhydrolyzable palmitoyl-CoA analog, antagonizes the effects of agonists on PPARalpha conformation and function in vitro.

Long-chain acyl-CoA esters and acyl-CoA binding protein are present in the nucleus of rat liver cells.

A detailed analysis of the subcellular distribution of acyl-CoA esters in rat liver revealed that significant amounts of long-chain acyl-CoA esters are present in highly purified nuclei. No contamination of microsomal or mitochondrial marker enzymes was detectable in the nuclear fraction. C16:1 and C18:3-CoA esters were the most abundant species, and thus, the composition of acyl-CoA esters in the nuclear fraction deviates notably from the overall composition of acyl-CoA esters in the cell.