Sodium bicarbonate cotransporters in the kidney contribute to the maintenance of whole body acid-base homeostasis. These integral membrane proteins play an important role in regulating intracellular pH and in mediating transepithelial sodium and bicarbonate tranport. Our understanding of the functional characteristics of these transporters has improved following the recent cloning of several members of the sodium bicarbonate cotranport (NBC) family. We have recently cloned and functionally characterized NBC3, a unique member of the NBC family which is stilbene-insensitive, electroneutral, and EIPA-inhibitable. In kidney, NBC3 is sorted to the apical membrane in type A intercalated cells and to the basolateral membrane in type B intercalated cells. Furthermore, NBC3 co-localized and co-immunoprecipitated with the vacuolar H+-ATPase have consensus PDZ-interacting domain, -ETAL and -DTAL respectively, which could play an important role in membrane sorting. On this basis, we screened a human kidney cDNA library in a yeast two-hybrid assay using the C-terminus of NBC3 as bait, and isolated a novel protein, NBC3BP, which has three potential PDZ-binding domains. NBC3BP was localized to the apical membrane of type A intercalated cells and was co-immunoprecipitated with NBC3 from kidney. We hypothesize that NBC3 and 58 kD subunit of the vacuolar H+-ATPase are sorted to the apical membrane of type A intercalated cells, via interaction of their C-terminal PDZ-interacting domains with the PDZ-binding protein, NBC3BP, which is expressed on the apical membrane of this cell type and not in type B intercalated cells. We will use the MDCK I cell line which sorts NBC3BP and NBC3 to the apical membrane similar to the type A intercalated cell as a model system for achieving the goals of this proposal. Successful completion of this project will enhance our understanding of the molecular mechanisms responsible for determining the polarity of acid-base transporters.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK058563-03
Application #
6635318
Study Section
General Medicine B Study Section (GMB)
Program Officer
Ketchum, Christian J
Project Start
2001-03-01
Project End
2005-12-31
Budget Start
2003-03-01
Budget End
2003-12-31
Support Year
3
Fiscal Year
2003
Total Cost
$289,750
Indirect Cost
Name
University of California Los Angeles
Department
Internal Medicine/Medicine
Type
Schools of Medicine
DUNS #
092530369
City
Los Angeles
State
CA
Country
United States
Zip Code
90095
Kurtz, Ira (2014) NBCe1 as a model carrier for understanding the structure-function properties of Na? -coupled SLC4 transporters in health and disease. Pflugers Arch 466:1501-16
Lacruz, R S; Smith, C E; Kurtz, I et al. (2013) New paradigms on the transport functions of maturation-stage ameloblasts. J Dent Res 92:122-9
Zhu, Quansheng; Shao, Xuesi M; Kao, Liyo et al. (2013) Missense mutation T485S alters NBCe1-A electrogenicity causing proximal renal tubular acidosis. Am J Physiol Cell Physiol 305:C392-405
Jiang, Jiansen; Magilnick, Nathaniel; Tsirulnikov, Kirill et al. (2013) Single particle electron microscopy analysis of the bovine anion exchanger 1 reveals a flexible linker connecting the cytoplasmic and membrane domains. PLoS One 8:e55408
Kurtz, Ira; Zhu, Quansheng (2013) Structure, function, and regulation of the SLC4 NBCe1 transporter and its role in causing proximal renal tubular acidosis. Curr Opin Nephrol Hypertens 22:572-83
Zhu, Quansheng; Liu, Weixin; Kao, Liyo et al. (2013) Topology of NBCe1 protein transmembrane segment 1 and structural effect of proximal renal tubular acidosis (pRTA) S427L mutation. J Biol Chem 288:7894-906
Burette, Alain C; Weinberg, Richard J; Sassani, Patrick et al. (2012) The sodium-driven chloride/bicarbonate exchanger in presynaptic terminals. J Comp Neurol 520:1481-92
Lacruz, Rodrigo S; Smith, Charles E; Moffatt, Pierre et al. (2012) Requirements for ion and solute transport, and pH regulation during enamel maturation. J Cell Physiol 227:1776-85
Kao, Liyo; Abuladze, Natalia; Shao, Xuesi M et al. (2012) A new technique for multiple re-use of planar patch clamp chips. J Neurosci Methods 208:205-10
Sergeev, Mikhail; Godin, Antoine G; Kao, Liyo et al. (2012) Determination of membrane protein transporter oligomerization in native tissue using spatial fluorescence intensity fluctuation analysis. PLoS One 7:e36215

Showing the most recent 10 out of 57 publications