| An 11-aa Peptide sequence near the cytoplasmic, C-terminus of human URAT1. The control peptide is 100% conserved in human URAT1/RST or OAT-4-like protein and only 54% in mouse RST/URAT1. Mammalian kidney and liver are critical in maintaining physiological ionic environment. Kidney specializes in removing toxins, drugs, and other organic anions from the blood by a process called renal secretion. Besides kidney, anionic substrates are also transported in other organs, e.g., choroid plexus, eye, airway, and placenta. Several multispecific OATs (OAT1-3, OAT-K1 and OATK2) and OATPs (organic anion transporting polypeptides, oatp1-3), have been cloned and characterized from various tissues. OATPs family of proteins are very similar in sequence and secondary protein structure (up to 12 transmembrane domains with cytoplasmic N and C-terminus). Urate, a naturally occurring product of purine metabolism, is a scavenger of oxidants. Urate exists primarily as a weak acid (pKa ~5.75). Urate concentration is quite high (~200-500 uM) in human due to loss of uricase gene and the presence of an effective reabsorption system. Recently an OAT-related transporter, URAT1, has been identified in the kidney that acts urate-anion exchanger and effectively regulates urate levels. URAT1/RST/SLC22A12 (mouse 553-aa, human 555-aa, chromosome 11q13, ~40kD) is ~42% identical with OAT4. Like OAT4, it is predicted to display 12-TM domains with cytoplasmic N and C-terminus. URTA1 is prominent is epithelial cells of proximal tubule of the renal cortex. Patients with idiopathic renal hypouricemia (lack of blood uric acid) have defects in URAT1 gene. Storage and Stability: Lyophilized powder may be stored at -20C. Stable for 12 months at -20C. Reconstitute with sterile buffer or ddH2O. Aliquot to avoid repeated freezing and thawing. Store at -20C. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap. Further dilutions can be made in assay buffer. |
