Inorganic phosphate (Pi) levels are hormonally regulated that affects the physiological activity of bone, kidney, and small intestine. Majority of the Pi is absorbed in the small intestine and reabsorbed in the proximal tubules in the kidney. At least 4 groups of structurally and funcationally related proteins are in involved in Pi transport: Type I-related NaPi transporters designated NPT1, Npt1, and NaPi-1 respectively in humans, mouse, and rabbit are expressed in the kidney and liver. Its expression and activity are not regulated by Pi deprivation or parathyroid hormone (PTH) and its role in Pi-homeostasis is not clear. Type IIa-related cotransporters, designated NaPi-2 in rat, NaPi-3 or NPT2 in humans, NaPi-4 in opposum, NaPi-5 in flounder vessel, NaPi-6 or Npt-2 in mouse, and NaPi-7 in rabbit, is the primary target for Pi regulation by dietary, hormonal, and tubular Pi reabsorption. Deletion of Npt2 gene produces severe Pi wasting. Type II transporters are expressed in kidney, brain, lung, bone and small intestine. Type IIb, designated as NaPi-IIB or NaPi-2b in rat/mouse, and NaPi-3b in human, is closely related isoform of the NaPi-2 family. It is expressed in small intestine and lung. Type III NaPi transporters, originally described as a family of cell surface receptors for gibbon ape leukemia virus (GALV) and murine amphotropic retrovirus (A-MuLv), share very low (<20%) sequence homology with Type I and II proteins, and are found in most tissues. Suitable for use in ELISA. Western Blot, though not tested, may potentially be used as an application. Other applications not tested.

Western Blot:1-10ug/ml using ECL. Under reducing conditions, 2 bands of 40-50kD are observed. Possible formation of multimeric structurres, 170 and 200kD. ELISA: 0.5-1ug/ml. Control peptide can be used to coat ELISA plates at 1ug/ml. Optimal dilutions to be determined by the researcher.

Control Peptide: N0035-25B NaPi-2AB, Human

May be stored at 4°C for short-term only. Aliquot to avoid repeated freezing and thawing. Store at -20°C. Aliquots are stable for 12 months. For maximum recovery of product, centrifuge the original vial after thawing and prior to removing the cap.

Synthetic peptide corresponding to aa206-225 from within the 2nd extracellular loop of human NPT2 conjugated to KLH.

Supplied as a liquid in PBS, 0.1% BSA.

Purified by immunoaffinity chromatography.

Recognizes human NaPi-2A. Species Sequence Homology: rat, mouse, sheep,100%; opposum, 95%; chicken, zebra fish, frog- 90%. The sequence is also highly conserved (~90%) in mouse, human and other species NPT2b/Type-Iib. Therefore, antibodies are expected to detect both Type2a and Type2b NPT2. No significant sequence homology is observed with other Pi-transporters (Type-I, III, or IV).