C-terminal topology of gastric H+,K+-ATPase

Asano, Shinji; Arakawa, S; Hirasawa, Masakazu; Sakai, Hideki; Ohta, Mitsuhiro; Ohta, Kiyoe; Takeguchi, Noriaki

doi:10.1042/bj2990059

Cited by 24 publications

(17 citation statements)

References 33 publications

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“…To check the expression of KCCs other than KCC4, anti-human KCC1 goat polyclonal antibody (Santa Cruz Biotechnology, Santa Cruz, CA), anti-rat KCC2 rabbit polyclonal antibody (Upstate Biotechnology, Lake Placid, NY), and anti-rat KCC3 rabbit polyclonal antibody (15) were used. Expression of gastric H ϩ ,K ϩ -ATPase was checked by using anti-mouse H ϩ ,K ϩ -ATPase ␣-subunit mouse monoclonal antibody (1H9) (Medical & Biological Laboratories Co., Nagoya, Japan), anti-mouse H ϩ ,K ϩ -ATPase ␤-subunit mouse monoclonal antibody (2B6) (Medical & Biological Laboratories Co.), and anti-hog H ϩ ,K ϩ -ATPase ␣-subunit rabbit polyclonal antibody (Ab1024) (16). Anti-rabbit Na ϩ ,K ϩ -ATPase ␣1 subunit mouse monoclonal antibody was obtained from Upstate Biotechnology.…”

Section: Methodsmentioning

confidence: 99%

Functional Association between K+-Cl- Cotransporter-4 and H+,K+-ATPase in the Apical Canalicular Membrane of Gastric Parietal Cells

Fujii

Takahashi

Ikari

et al. 2009

Journal of Biological Chemistry

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We studied whether K ؉ -Cl ؊ cotransporters (KCCs) are involved in gastric HCl secretion. We found that KCC4 is expressed in the gastric parietal cells more abundantly at the luminal region of the gland than at the basal region. KCC4 was found in the stimulation-associated vesicles (SAV) derived from the apical canalicular membrane but not in the intracellular tubulovesicles, whereas H ؉ ,K ؉ -ATPase was expressed in both of them. In contrast, KCC1, KCC2, and KCC3 were not found in either SAV or tubulovesicles.

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Section: Methodsmentioning

confidence: 99%

Functional Association between K+-Cl- Cotransporter-4 and H+,K+-ATPase in the Apical Canalicular Membrane of Gastric Parietal Cells

Fujii

Takahashi

Ikari

et al. 2009

Journal of Biological Chemistry

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“…The membranes were blocked with a 4% Block Ace solution (Dainippon Pharmaceutical Co.). The proteins were detected with an anti-gastric proton pump ␣-subunit antibody, Ab1024, which recognizes the carboxyl terminal peptide (residues 1024 -1034) (28). After incubation with a horseradish peroxidase-conjugated anti-rabbit …”

Section: Methodsmentioning

confidence: 99%

The Cavity Structure for Docking the K+-competitive Inhibitors in the Gastric Proton Pump

Asano¹,

Yoshida

Yashiro

et al. 2004

Journal of Biological Chemistry

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2-Methyl-8-(phenylmethoxy)imidazo[1,2-a]pyridine-3-acetonitrile (SCH 28080) is a reversible inhibitor specific for the gastric proton pump. The inhibition pattern is competitive with K ؉ . Here we studied the binding sites of this inhibitor on the putative three-dimensional structure of the gastric proton pump ␣-subunit that was constructed by homology modeling based on the structure of sarcoplasmic reticulum Ca 2؉ pump. Alanine and serine mutants of Tyr 801 located in the fifth transmembrane segment of the gastric proton pump ␣-subunit retained the 86 Rb transport and K ؉ -dependent ATPase (K ؉ -ATPase) activities. These mutants showed 60 -80-times lower sensitivity to SCH 28080 than the wild type in the 86 Rb transport activity. The K ؉ -ATPase activities of these mutants were not completely inhibited by SCH 28080. The sensitivity to SCH 28080 was dependent on the bulkiness of the side chain at this position. Therefore, the side chain of Tyr 801 is important for the interaction with this inhibitor. In the three-dimensional structure of the E 2 form (conformation with high affinity for K ؉ ) of the gastric proton pump, Tyr 801 faces a cavity surrounded by the first, fourth, fifth, sixth, and eighth transmembrane segments and fifth/sixth, seventh/eighth, and ninth/tenth loops. SCH 28080 can dock in this cavity. However, SCH 28080 cannot dock in the same location in the E 1 form (conformation with high affinity for proton) of the gastric proton pump due to the drastic rearrangement of the transmembrane helices between the E 1 and E 2 forms. These results support the idea that this cavity is the binding pocket of SCH 28080.The gastric H ϩ ,K ϩ -ATPase is a proton pump that is responsible for gastric acid secretion (1). This pump consists of two kinds of subunits, the ␣-and ␤-subunits. The ␣-subunit is the catalytic subunit containing 10 transmembrane segments. The ATP binding site (2, 3) and the cation binding sites are located on this subunit (4 -10). The ␤-subunit is the non-catalytic glycoprotein containing a single transmembrane segment and is involved in stabilization as well as targeting of the ␣-subunit to the plasma membrane (11). This pump belongs to the family of type II P-type ATPases, which include sarcoplasmic reticulum (SR) 1 Ca 2ϩ -ATPase (Ca 2ϩ pump) and Na ϩ ,K ϩ -ATPase (Na ϩ pump) (12).At present, inhibitors specific for the gastric proton pump are classified into two groups. Irreversible inhibitors such as omeprazole, rabeprazole, and lansoprazole, termed the proton pump inhibitors, are the first group. They are activated in acidic lumens, modify the cysteine residues located on the luminal side of the proton pump, and inhibit its pump activity. They are clinically used for controlling hyperacidity. The second classified group of specific proton pump inhibitors are the reversible inhibitors such as SCH 28080 (13) and 3-amino-5-methyl-2-(2-methyl-3-thienyl)imidazo[1,2-a]thieno[3,2-c]pyridine (SPI-447) (Fig. 1) (14), which are described as acid pump antagonists (APAs). They bind to the E 2 or E 2...

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“…An affinity-purified rabbit polyclonal antibody against gastric H ϩ ,K ϩ -ATPase ␣1-subunit was kindly provided by Dr. Noriaki Takeguchi (Toyama Medical and Pharmaceutical University) (2). The immunohistochemistry was performed as reported previously (26,32).…”

Section: Animalsmentioning

confidence: 99%

Gastric type H⁺,K⁺-ATPase in the cochlear lateral wall is critically involved in formation of the endocochlear potential

Shibata

Hibino²,

Doi³

et al. 2006

American Journal of Physiology-Cell Physiology

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Cochlear endolymph has a highly positive potential of approximately +80 mV known as the endocochlear potential (EP). The EP is essential for hearing and is maintained by K+ circulation from perilymph to endolymph through the cochlear lateral wall. Various K+ transport apparatuses such as the Na+,K+-ATPase, the Na+-K+-2Cl− cotransporter, and the K+ channels Kir4.1 and KCNQ1/KCNE1 are expressed in the lateral wall and are known to play indispensable roles in cochlear K+ circulation. The gastric type of the H+,K+-ATPase was also shown to be expressed in the cochlear lateral wall (Lecain E, Robert JC, Thomas A, and Tran Ba Huy P. Hear Res 149: 147–154, 2000), but its functional role has not been well studied. In this study we examined the precise localization of H+,K+-ATPase in the cochlea and its involvement in formation of EP. RT-PCR analysis showed that the cochlea expressed mRNAs of gastric α1-, but not colonic α2-, and β-subunits of H+,K+-ATPase. Immunolabeling of an antibody specific to the α1 subunit was detected in type II, IV, and V fibrocytes distributed in the spiral ligament of the lateral wall and in the spiral limbus. Strong immunoreactivity was also found in the stria vascularis. Immunoelectron microscopic examination exhibited that the H+,K+-ATPase was localized exclusively at the basolateral site of strial marginal cells. Application of Sch-28080, a specific inhibitor of gastric H+,K+-ATPase, to the spiral ligament as well as to the stria vascularis caused prominent reduction of EP. These results may imply that the H+,K+-ATPase in the cochlear lateral wall is crucial for K+ circulation and thus plays a critical role in generation of EP.

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C-terminal topology of gastric H+,K+-ATPase

Cited by 24 publications

References 33 publications

Functional Association between K+-Cl- Cotransporter-4 and H+,K+-ATPase in the Apical Canalicular Membrane of Gastric Parietal Cells

Functional Association between K+-Cl- Cotransporter-4 and H+,K+-ATPase in the Apical Canalicular Membrane of Gastric Parietal Cells

The Cavity Structure for Docking the K+-competitive Inhibitors in the Gastric Proton Pump

Gastric type H⁺,K⁺-ATPase in the cochlear lateral wall is critically involved in formation of the endocochlear potential

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C-terminal topology of gastric H+,K+-ATPase

Cited by 24 publications

References 33 publications

Functional Association between K+-Cl- Cotransporter-4 and H+,K+-ATPase in the Apical Canalicular Membrane of Gastric Parietal Cells

Functional Association between K+-Cl- Cotransporter-4 and H+,K+-ATPase in the Apical Canalicular Membrane of Gastric Parietal Cells

The Cavity Structure for Docking the K+-competitive Inhibitors in the Gastric Proton Pump

Gastric type H+,K+-ATPase in the cochlear lateral wall is critically involved in formation of the endocochlear potential

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Gastric type H⁺,K⁺-ATPase in the cochlear lateral wall is critically involved in formation of the endocochlear potential