Human ATP1AL1 gene encodes a ouabain-sensitive H-K-ATPase

1995 ◽  
Vol 269 (4) ◽  
pp. C992-C997 ◽  
Author(s):  
N. N. Modyanov ◽  
P. M. Mathews ◽  
A. V. Grishin ◽  
P. Beguin ◽  
A. T. Beggah ◽  
...  
Keyword(s):  
Structural Features ◽  
Alpha Subunit ◽  
Extracellular Potassium ◽  
Xenopus Laevis Oocytes ◽  
Proton Extrusion ◽  
Atpase Gene ◽  
High Concentrations ◽  
Ouabain Inhibition ◽  
P Type ◽  
K Transport

The cDNA for ATP1AL1, the fifth member of the human Na-K-adenosinetriphosphatase (ATPase)/H-K-ATPase gene family, was recently cloned (A. V. Grishin, V. E. Sverdlov, M. B. Kostina, and N. N. Modyanov. FEBS Lett. 349: 144-150, 1994). The encoded protein (ATP1AL1) has all the primary structural features common to the catalytic alpha-subunit of ion-transporting P-type ATPases and is similar (63-64% identity) to the Na-K-ATPase alpha-subunit isoforms and the gastric H-K-ATPase alpha-subunit. In this study, ATP1AL1 was expressed in Xenopus laevis oocytes in combination with the beta-subunit of rabbit gastric H-K-ATPase. The functional properties of the stable alpha/beta-complex were studied by 86Rb+ uptake and demonstrated that ATP1AL1 is a novel human K(+)-dependent ATPase [apparent half-constant activation/(K1/2) for K+ approximately 375 microM)]. ATP1AL1-mediated inward K+ transport was inhibited by ouabain (inhibition constant approximately 13 microM) and was found to be inhibited by high concentrations of SCH-28080 (approximately 70% at 500 microM). ATP1AL1 expression resulted in the alkalinization of the oocytes' cytoplasm and ouabain-sensitive proton extrusion, as measured with pH-sensitive microelectrodes. These data argue that ATP1AL1 is the catalytic alpha-subunit of a human nongastric P-type ATPase capable of exchanging extracellular potassium for intracellular protons.

Primary structure and functional expression of the mouse and frog alpha-subunit of the gastric H(+)-K(+)-ATPase

1995 ◽  
Vol 268 (5) ◽  
pp. C1207-C1214 ◽  
Author(s):  
P. M. Mathews ◽  
D. Claeys ◽  
F. Jaisser ◽  
K. Geering ◽  
J. D. Horisberger ◽  
...  
Keyword(s):  
Xenopus Oocytes ◽  
Gastric Gland ◽  
Functional Expression ◽  
Alpha Subunit ◽  
Atpase Inhibitor ◽  
Proton Extrusion ◽  
K Uptake ◽  
The Family ◽  
P Type ◽  
Gastric Parietal Cells

The H(+)-K(+)-ATPase of the gastric parietal cells is responsible for the acidification of the stomach lumen. This heterodimeric protein belongs to the family of cation-translocating P-type ATPases, which includes the closely related Na(+)-ATPase. We have cloned the alpha-subunit cDNA of the Xenopus and murine gastric H(+)-K(+)-ATPase (alpha H-K). We have expressed Xenopus and murine alpha H-K along with the previously cloned gastric H(+)-K(+)-ATPase beta-subunit of rabbit (beta H-K) in Xenopus oocytes by cRNA injection. An antibody directed against the beta H-K coimmunoprecipitates under nondenaturing conditions the alpha H-K of both species, demonstrating assembly of the alpha/beta complex. Additionally, we demonstrate the presence of K(+)-transporting H(+)-K(+)-ATPase in the plasma membrane of oocytes by 86Rb- uptake. The H(+)-K(+)-ATPase-mediated K+ uptake was inhibited by the gastric H(+)-K(+)-ATPase inhibitor Sch-28080, but not by ouabain, and shows K(+)-dependent activation (K1/2 approximately 2 mM). Furthermore, H(+)-K(+)-ATPase-expressing oocytes show a Sch-28080 inhibitable proton extrusion. Our data indicate that the expressed H(+)-K(+)-ATPase behaves functionally in oocytes as in the gastric gland.

Cloning of an aquaporin homologue present in water channel containing endosomes of toad urinary bladder

1996 ◽  
Vol 270 (1) ◽  
pp. C372-C381 ◽  
Author(s):  
J. Siner ◽  
A. Paredes ◽  
C. Hosselet ◽  
T. Hammond ◽  
K. Strange ◽  
...  
Keyword(s):  
Urinary Bladder ◽  
Water Channel ◽  
Structural Features ◽  
Xenopus Laevis Oocytes ◽  
Sequence Motif ◽  
Toad Urinary Bladder ◽  
Cytoplasmic Vesicles ◽  
Terrestrial Habitats ◽  
Total Body

Regulation of total body water balance in amphibians by antidiuretic hormone (ADH) contributed to their successful colonization of terrestrial habitats approximately 200-300 million years ago. In the mammalian kidney, ADH modulates epithelial cell apical membrane water permeability (Pf) by fusion and retrieval of cytoplasmic vesicles containing water channel proteins called aquaporins (AQPs). To determine the role of AQPs in ADH-elicited Pf in amphibians, we have identified and characterized a unique AQP from Bufo marinus called AQP toad bladder (AQP-TB). AQP-TB possesses many structural features common to other AQPs, AQP-TB is expressed abundantly in ADH-responsive tissues, including toad urinary bladder and skin as well as lung, skeletal muscle, kidney, and brain. In a manner identical to that reported for the mammalian ADH-elicited water channel AQP2, AQP-TB expression is increased significantly by intervals of dehydration or chronic ADH stimulation. However, expression of AQP-TB protein in Xenopus laevis oocytes does not significantly increase oocyte Pf. The lack of expression of functional AQP-TB water channels in oocytes may result from intracellular sequestration of AQP-TB due to the presence of a YXRF sequence motif present in its carboxyterminal domain.

Concentration-Dependent Photoluminescence and Raman of p-Type GaAs Grown in a Metallic-Arsenic-Based-MOCVD System

2008 ◽  
Vol 587-588 ◽  
pp. 283-287
Author(s):  
J. Díaz-Reyes ◽  
Miguel Galvan-Arellano ◽  
R. Peña-Sierra
Keyword(s):  
Hole Concentration ◽  
Radiative Transitions ◽  
Growth Atmosphere ◽  
Scattering Spectra ◽  
Van Der Pauw ◽  
High Concentrations ◽  
Raman Scattering Spectra ◽  
P Type ◽  
Photoluminescence Response

This work presents the optical and structural characterization of p-type GaAs epilayers. The gallium precursor was the organometallic compound trimethylgallium (TMG). The influence of the doping in the optical and structural properties of the GaAs layers has been studied by photoluminescence (PL) and Raman dispersion measurements. The range of analyzed hole concentration was from 1017 to 1019 cm-3 as measured by the Hall-van der Pauw method. For carrying out doping p-type, it was necessary to modify the hydrogen activity in the growth atmosphere with the control of a H2+N2 mixture, which was used like transporting gas. The photoluminescence response and Raman dispersion of the layers are strongly dependence of the growth temperature, which were investigated based on the hole concentration. The PL response of the layers shows two radiative transitions, band-to-band and band-to-C-acceptor at low hole concentration and disappears at high concentrations. Raman scattering spectra show LO mode at 270 cm-1 for low doped samples and a LO-like mode at 290 cm-1 produced by the phonon-holeplasmon coupling for high doped samples.

Ouabain-sensitive liver and diaphragm respiration in cold-acclimated hamster

1977 ◽  
Vol 42 (2) ◽  
pp. 150-153 ◽  
Author(s):  
B. A. Horwitz ◽  
M. Eaton
Keyword(s):  
Transport System ◽  
Cold Exposure ◽  
Driving Force ◽  
Energy Demands ◽  
Before And After ◽  
Ouabain Inhibition ◽  
K Transport

The in vitro respiratory rates of liver and diaphragm from hamsters were compared before and after prolonged cold exposure (5 degrees C, 3–4 wk). In the presence or absence of glucose, respiratory rates were elevated in both tissues from the cold-acclimated hamsters, and these cold-induced increases were significantly reduced by ouabain. This ouabain inhibition is consistent with the hypothesis that cold exposure of these rodents stimulates the energy demands of the Na+/K+ transport system in liver and diaphragm, with these demands providing a driving force, at least in part, for respiration and accompanying cellular thermogenesis.

Theory of Defects, Doping, Surfaces and Interfaces in Wide Gap Nitrides

1996 ◽  
Vol 423 ◽  
Author(s):  
J. Bernholc ◽  
P. Boguslawski ◽  
E. L. Briggs ◽  
M. Buongiorno Nardelli ◽  
B. Chen ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
Group Iv ◽  
Type I ◽  
Shallow Acceptor ◽  
Surface And Interface ◽  
Al Content ◽  
Surfaces And Interfaces ◽  
High Concentrations ◽  
P Type ◽  
High Al Content

AbstractThe results of extensive theoretical studies of group IV impurities and surface and interface properties of nitrides are presented and compared with available experimental data. Among the impurities, we have considered substitutional C, Si, and Ge. CN is a very shallow acceptor, and thus a promising p-type dopant. Both Si and Ge are excellent donors in GaN. However, in AlGaN alloys the DX configurations are stable for a sufficiently high Al content, which quenches the doping efficiency. At high concentrations, it is energetically favorable for group IV impurities to form nearest-neighbor Xcation-XN pairs. Turning to surfaces, AIN is known to exhibit NEA. We find that the NEA property depends sensitively on surface reconstruction and termination. At interfaces, the strain effects on the band offsets range from 20% to 40%, depending on the substrate. The AIN/GaN/InN interfaces are all of type I, while the A10.5Ga0.5 N/A1N zinc-blende (001) interface may be of type II. Further, the calculated bulk polarizations in wurtzite AIN and GaN are -1.2 and -0.45 μC/cm2, respectively, and the interface contribution to the polarization in the GaN/AlN wurtzite multi-quantum-well is small.

scholarly journals Molecular cloning of the rat integrin alpha 1-subunit: a receptor for laminin and collagen.

1990 ◽  
Vol 111 (2) ◽  
pp. 709-720 ◽  
Author(s):  
M J Ignatius ◽  
T H Large ◽  
M Houde ◽  
J W Tawil ◽  
A Barton ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Signal Sequence ◽  
Structural Features ◽  
Alpha Subunit ◽  
Relative Molecular Mass ◽  
Sequence Motif ◽  
Binding Domains ◽  
Process Outgrowth ◽  
Adhesive Interactions ◽  
Strong Candidate

Integrin heterodimers mediate a variety of adhesive interactions, including neuronal attachment to and process outgrowth on laminin. We report here the cloning and primary sequence of an M-200 kD integrin alpha subunit that associates with the integrin beta 1 subunit to form a receptor for both laminin and collagen. Similarities in ligand-binding specificity, relative molecular mass and NH2-terminal sequence make this a strong candidate for the rat homologue of the alpha subunit of the human integrin VLA-1. The full-length rat alpha 1 cDNAs encode a protein containing a purative signal sequence and a mature polypeptide of 1,152 amino acids, with extracellular, transmembrane and cytoplasmic domains. Several structural features are conserved with other integrin alpha chains, including (a) a sequence motif repeated seven times in the NH2-terminal half; (b) potential Ca2+/Mg2+ binding sites in repeats 5, 6, and 7, and (c) alignment of at least 14 of 23 cysteine residues. This rat alpha 1 sequence also contains a 206-amino acid I domain, inserted between repeats 2 and 3, that is homologous to I domains found in the same position in the alpha subunits of several integrins (VLA-2, Mac-1, LFA-1, p150). The rat alpha 1 and human VLA-2 apha subunits share greater than 50% sequence identity in the seven repeats and I domain, suggesting that these sequence identities may underlie some of their similar ligand-binding specificities. However, the rat integrin alpha 1 subunit has several unique features, including a 38-residue insert between two Ca2+/Mg2+ binding domains, and a divergent 15-residue cytoplasmic sequence, that may potentially account for unique functions of this integrin.

Analysis of subunit assembly of the Na-K-ATPase

1994 ◽  
Vol 266 (3) ◽  
pp. C579-C589 ◽  
Author(s):  
D. M. Fambrough ◽  
M. V. Lemas ◽  
M. Hamrick ◽  
M. Emerick ◽  
K. J. Renaud ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Sodium Pump ◽  
Beta Subunit ◽  
Alpha Subunit ◽  
Beta Subunits ◽  
Limited Region ◽  
Subunit Assembly ◽  
Alpha Subunits ◽  
Subunit Isoforms ◽  
P Type

The Na-K-ATPase, or sodium pump, is comprised of two subunits, alpha and beta. Each subunit spans the lipid bilayer of the cell membrane. This review summarizes our efforts to determine how the two subunits interact to form the functional ion transporter. Our major approach has been to observe the potential for subunit assembly when one or both subunits are truncated or present as chimeras that retain only a limited region of the Na-K-ATPase. DNAs encoding these altered subunit forms of the avian Na-K-ATPase are expressed in mammalian cells. Monoclonal antibodies specific for the avian beta-subunit are then used to purify newly synthesized avian beta-subunits, and the presence of accompanying alpha-subunits indicates that subunit assembly has occurred. The ectodomain of the beta-subunit (approximately residues 62-304) is sufficient for assembly with the alpha-subunit, and a COOH-terminal truncation of the beta-subunit that lacks aminoacyl residues beyond 162 will assemble inefficiently. A maximum of 26 aminoacyl residues of the alpha-subunit are necessary for robust assembly with the beta-subunit, when this sequence replaces the COOH-terminal half of the loop between membrane spans 7 and 8 in the SERCA1 Ca-ATPase. This region of the Ca-ATPase faces the lumen of the endoplasmic reticulum. These findings encourage study of other related questions, including whether there is preferential assembly of certain subunit isoforms and how various P-type ATPases are targeted to their appropriate subcellular compartments.

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