Biomaterial Database

Kinetic characterization of a stably expressed novel Na+/H+ exchanger (NHE-2). 1993

T Honda, and S M Knobel, and N M Bulus, and F K Ghishan

Department of Pediatric Gastroenterology/Nutrition, Vanderbilt University Medical Center, Nashville, TN.

We have recently reported the molecular cloning, sequencing and tissue distribution of a novel Na+/H+ exchanger (NHE-2). The cDNA for NHE-2 was cloned by screening a rat intestinal cDNA library. This clone was unique due to the fact that it lacks the first two transmembrane domains which are present in the other Na+/H+ exchanger isoforms (NHE-1, NHE-3, NHE-4). This structural change in the cDNA offered a unique opportunity to study in detail the properties of this stably expressed cDNA in chinese lung fibroblasts that lack the Na+/H+ exchanger (PS120) cells. Amiloride-sensitive Na+ uptake was linear up to 2 min in PS120 cells transfected with the cDNA. Kinetics of the amiloride-sensitive Na+ uptake showed a Vmax of 24.7 +/- 5 nmol/microliters ICW per min and a Km of 33.1 +/- 2.0 mM. The inhibitory constant (KI) for amiloride and its analogue 5-N-ethyl-N-isopropylamiloride (EIPA) was 0.15 microM and 0.66 microM, respectively. Epidermal growth factor, a known stimulator of NHE-1, also upregulated the expressed NHE-2. These results characterize the kinetic properties of this unique exchanger and suggests that the first two transmembrane domains of the Na+/H+ exchanger isoforms are not essential for the expression of amiloride-sensitive Na+ uptake.

UI	MeSH Term	Description	Entries
D007700	Kinetics	The rate dynamics in chemical or physical systems.
D002352	Carrier Proteins	Proteins that bind or transport specific substances in the blood, within the cell, or across cell membranes.	Binding Proteins,Carrier Protein,Transport Protein,Transport Proteins,Binding Protein,Protein, Carrier,Proteins, Carrier
D002460	Cell Line	Established cell cultures that have the potential to propagate indefinitely.	Cell Lines,Line, Cell,Lines, Cell
D003412	Cricetulus	A genus of the family Muridae consisting of eleven species. C. migratorius, the grey or Armenian hamster, and C. griseus, the Chinese hamster, are the two species used in biomedical research.	Hamsters, Armenian,Hamsters, Chinese,Hamsters, Grey,Armenian Hamster,Armenian Hamsters,Chinese Hamster,Chinese Hamsters,Grey Hamster,Grey Hamsters,Hamster, Armenian,Hamster, Chinese,Hamster, Grey
D004815	Epidermal Growth Factor	A 6-kDa polypeptide growth factor initially discovered in mouse submaxillary glands. Human epidermal growth factor was originally isolated from urine based on its ability to inhibit gastric secretion and called urogastrone. Epidermal growth factor exerts a wide variety of biological effects including the promotion of proliferation and differentiation of mesenchymal and EPITHELIAL CELLS. It is synthesized as a transmembrane protein which can be cleaved to release a soluble active form.	EGF,Epidermal Growth Factor-Urogastrone,Urogastrone,Human Urinary Gastric Inhibitor,beta-Urogastrone,Growth Factor, Epidermal,Growth Factor-Urogastrone, Epidermal,beta Urogastrone
D006224	Cricetinae	A subfamily in the family MURIDAE, comprising the hamsters. Four of the more common genera are Cricetus, CRICETULUS; MESOCRICETUS; and PHODOPUS.	Cricetus,Hamsters,Hamster
D000584	Amiloride	A pyrazine compound inhibiting SODIUM reabsorption through SODIUM CHANNELS in renal EPITHELIAL CELLS. This inhibition creates a negative potential in the luminal membranes of principal cells, located in the distal convoluted tubule and collecting duct. Negative potential reduces secretion of potassium and hydrogen ions. Amiloride is used in conjunction with DIURETICS to spare POTASSIUM loss. (From Gilman et al., Goodman and Gilman's The Pharmacological Basis of Therapeutics, 9th ed, p705)	Amidal,Amiduret Trom,Amiloberag,Amiloride Hydrochloride,Amiloride Hydrochloride, Anhydrous,Kaluril,Midamor,Midoride,Modamide,Anhydrous Amiloride Hydrochloride,Hydrochloride, Amiloride,Hydrochloride, Anhydrous Amiloride,Trom, Amiduret
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001692	Biological Transport	The movement of materials (including biochemical substances and drugs) through a biological system at the cellular level. The transport can be across cell membranes and epithelial layers. It also can occur within intracellular compartments and extracellular compartments.	Transport, Biological,Biologic Transport,Transport, Biologic
D012964	Sodium	A member of the alkali group of metals. It has the atomic symbol Na, atomic number 11, and atomic weight 23.	Sodium Ion Level,Sodium-23,Ion Level, Sodium,Level, Sodium Ion,Sodium 23