Description_x000D_ Biochem/physiol Actions_x000D_ There is evidence that a group of closely related nuclear receptors, called peroxisome proliferator-activated receptors (PPARs), may be involved in chronic diseases such as diabetes, obesity, artherosclerosis and cancer. The PPARs were first cloned as the nuclear receptors that mediate the effects of synthetic compounds called peroxisome proliferators on gene transcription. It soon became clear that eicosanoids and fatty acids can also regulate gene transcription through PPARs. They bind a specific element in the promoter region of target genes only as a heterodimer with the receptor for 9-cis retinoic acid, RXR (retinoid X receptor). Binding of the ligand of either receptor can activate the complex, but binding of both ligands simultaneously is more potent. Three PPAR isotypes have been identified: α, β (also called NUC1) and γ. PPAR α is expressed most in brown adipose tissue and liver, then kidney, heart and skeletal muscle. PPAR β is found in many tissues but the highest expression is in the gut, kidney and heart. PPAR γ is mainly expressed in adipose tissue, and to a lesser extent in colon, the immune system and the retina. The target genes of PPAR α are a relatively homogenous group of genes that participate in aspects of lipid catabolism such as fatty acid uptake through membranes, fatty acid binding in cells, fatty acid oxidation (in microsomes, peroxisomes and mitochondria) and lipoprotein assembly and transport._x000D_ Physical form_x000D_ Clear and colorless frozen liquid solution_x000D_ Preparation Note_x000D_ Use a manual defrost freezer and avoid repeated freeze-thaw cycles. While working, please keep sample on ice.