| Bicarbonate, along with CO2, is the major pH buffer of biological fluids. The inter-conversion of CO2 to HCO3- is mediated by family of carbonic anhydrases. Several organs specialize in the mobilization of HCO3-. The pancreatic ducts move CO2 and HCO3- from the blood into pancreatic secretions. The kidneys reabsorb massive amount of HCO3- daily (amount of NaHCO3 contained in 1 Ib of baking soda) through the glomerular flirtation of ~180 liters of plasma. To prevent a massive acidosis, the proximal tubules (PT) cells in the nephron subsequently reabsorb virtually all of HCO3-, as well as most of the filtered Na+, Cl-, and H2O. A great majority of HCO3- reabsorption occurs via trans-cellular coupling of the luminal Na-H+ exchanger 3 and Na+-H+ ATPase with the basolateral Na+ HCO3- cotransporters (NBC). Several related proteins constitute the emerging NBC family (NBC1-3) of membrane cotransporters that are found in a variety of epithelial and non-epithelial tissues, and may be tissue specific. Physiologically, NBC is electrogenic, Na+ and HCO3- dependent, Cl- independent, and inhibited by stilbenes (DIDS and SITS). The NBC family of proteins are 30-35% related to anion exchangers (AE2 and AE3, SLC4A1-SLC4A3) and display the same protein topology: (a) At least 10 TM domains with both the N and C-termini predicted to be intracellular, (b) presence of a large, glycosylated, extracellular loop between TM5 and TM6, and (c) the lysine residues are conserved at predicted DIDS-reactive sites. NBC3 (SLC4A), mouse 1089 aa, human 1044 aa) has 3 three transcripts, which are expressed in a tissue specific manner (9 kb in brain, placenta, lung, liver, muscle, kidney, pancreas, stomach, thyroid, and adrenal etc). NBC3 has two variants. NBC3 is 56% identical with NBC1 and 76% with NBC2. Applications: Suitable for use in ELISA, Western Blotting. Other applications not tested. Recommended Dilution: Western Blotting 1-10ug/ml for affinity pure using Chemiluminescence technique. ELISA: 1:10,000-1:100,000 using 50-100ng of control peptide/well. Optimal dilutions to be determined by the researcher. Storage and Stability: May be stored at 4C for short-term only. For long-term storage and to avoid repeated freezing and thawing, aliquot and add glycerol (40-50%). Freeze at -20C. Aliquots are stable for at least 12 months 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. |
