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K Munson

Publications and source records attributed to K Munson.

At least 19 recordsLinked to original sources
PubMed2002

SCH28080, a K+-competitive inhibitor of the gastric H,K-ATPase, binds near the M5-6 luminal loop, preventing K+ access to the ion binding domain.

Inhibition of the gastric H,K-ATPase by the imidazo[1,2-alpha]pyridine, SCH28080, is strictly competitive with respect to K+ or its surrogate, NH4+. The inhibitory kinetics [V(max), K(m,app)(NH4+), K(i)(SCH28080), and competitive, mixed, or noncompetitive] of mutants can define the inhibitor binding domain and the route to the ion binding region within M4-6. While mutations Y799F, Y802F, I803L, S806N, V807I (M5), L811V (M5-6), Y928H (M8), and Q905N (M7-8) had no effect on inhibitor kinetics, mutations P798C, Y802L, P810A, P810G, C813A or -S, I814V or -F, F818C, T823V (M5, M5-6, and M6), E914Q, F917Y, G918E, T929L, and F932L (M7-8 and M8) reduced the affinity for SCH28080 up to 10-fold without affecting the nature of the kinetics. In contrast, the L809F substitution in the loop between M5 and M6 resulted in an approximately 100-fold decrease in inhibitor affinity, and substitutions L809V, I816L, Y925F, and M937V (M5-6, M6, and M8) reduced the inhibitor affinity by 10-fold, all resulting in noncompetitive kinetics. The mutants L811F, Y922I, and I940A also reduced the inhibitor affinity up to 10-fold but resulted in mixed inhibition. The mutations I819L, Q923V, and Y925A also gave mixed inhibition but without a change in inhibitor affinity. These data, and the 9-fold loss of SCH28080 affinity in the C813T mutant, suggest that the binding domain for SCH28080 contains the surface between L809 in the M5-6 loop and C813 at the luminal end of M6, approximately two helical turns down from the ion binding region, where it blocks the normal ion access pathway. On the basis of a model of the Ca-ATPase in the E2 conformation (PDB entry 1kju), the mutants that change the nature of the kinetics are arranged on one side of M8 and on the adjacent side of the M5-6 loop and M6 itself. This suggests that mutations in this region modify the enzyme structure so that K+ can access the ion binding domain even with SCH28080 bound.

Amino Acid Sequence↗
PubMed2001

Proximity of transmembrane segments M3 and M1 of the alpha subunit of Na+,K+-ATPase revealed by specific oxidative cleavage mediated by a complex of Cu2+ ions and 4,7-diphenyl-1,10-phenanthroline.

This paper describes a novel approach to specific oxidative cleavage of Na(+),K(+)-ATPase, mediated by Cu(2+) ions and a hydrophobic phenanthroline, 4,7-diphenyl-1,10-phenanthroline (DPP), in the presence of ascorbate and H(2)O(2). The cleavage produces two major fragments of the alpha subunit, with apparent molecular masses of 96.5 and 76 kDa, and N-termini near the cytoplasmic entrance of transmembrane segments M1 and M3, respectively, The kinetics indicate that both cleavages are mediated by a single Cu(2+)-DPP complex. We infer that M3 and M1 are in proximity near the cytoplasmic surface. The yields of 96.5 and 76 kDa fragments are not significantly affected by ligands that stabilize different E(1) and E(2) conformations. In E(2)(K) and E(2)P conformations, a minor 5.5 kDa fragment with its N-terminus in M10 is also observed. The 96.5 and 76 kDa fragments are indistinguishable from two fragments near M3 and M1 produced by Fe(2+)-catalyzed cleavage described previously [Goldshleger, R., and Karlish, S. J. D. (1999) J. Biol. Chem. 274, 16213-16221], whereas other Fe(2+)-catalyzed cleavage fragments in the cytoplasmic P and A domains are not observed with the Cu(2+)-DPP complex. These findings provide experimental support for the concept of two separate Fe(2+) sites. A homology model, with Na(+),K(+)-ATPase residues within transmembrane segments and connecting loops substituted into the crystal structure of Ca(2+)-ATPase, shows the proximity between the sequences HFIH in M3 and EVWK in M1, near the cytoplasmic surface. Thus, the model strongly supports the conclusions based on cleavages mediated by the Cu(2+)-DPP complex (or Fe(2+) at site 2). As a corollary, the cleavages provide evidence for similar packing of M1 and M3 of Na(+),K(+)-ATPase and Ca(2+)-ATPase.

Amino Acid Sequence↗
PubMed2001

Mutational analysis of the K+-competitive inhibitor site of gastric H,K-ATPase.

The gastric H,K-ATPase is inhibited selectively and K(+)-competitively from its luminal surface by protonated imidazo[1,2alpha]pyridines (e.g., SCH28080). Identification of the amino acids in the membrane domain that affect SCH28080 inhibition should provide a template for modeling a luminally directed vestibule in this enzyme, based on the crystal structure of the sr Ca-ATPase. Five conserved carboxylic residues, Glu343, Glu795, Glu820, Asp824, Glu936, and unique Lys791 in the H,K-ATPase were mutated, and the effects of mutations on the K(i) for SCH28080, V(max), and K(m,app)[NH(4)(+)] were measured. A kinetic analysis of the ATP hydrolysis data indicated that all of these residues significantly affect the interaction of NH(4)(+) ions with the protein but only three of them, Glu795, Glu936, and Lys791, greatly affected SCH28080 inhibition. A Glu795Asp mutation increased the K(i) from 64 +/- 11 to 700 +/- 110 nM. Since, however, the mutation Glu795Gln did not change the K(i) (86 +/- 31 nM), this site has a significant spatial effect on inhibitor kinetics. A Glu936Asp mutation resulted in noncompetitive kinetics while Gln substitution had no effect either on inhibitor affinity or on the nature of the kinetics, suggesting that the length of the Glu936 side chain is critical for the exclusive binding of the ion and SCH28080. Mutation of Lys791 to Ser, the residue present in the SCH28080-insensitive Na,K-ATPase, resulted in a 20-fold decrease in SCH28080 affinity, suggesting an important role of this residue in SCH28080 selectivity of the H,K-ATPase versus Na,K-ATPase. Mutations of Asp824, Glu343, and Glu820 increased the K(i) 2-3-fold, implying a relatively minor role for these residues in SCH28080 inhibition. It appears that the imidazopyridine moiety of SCH28080 in the protonated state interacts with residues near the negatively charged residues of the empty ion site from the luminal side (TM4, -5, -6, and -8) while the hydrophobic phenyl ring interacts with TM1 or TM2 (the latter conclusion based on previous data from photoaffinity labeling). The integrity of the SCH28080 binding site depends on the presence of Lys791, Glu936, and Glu795 in H,K-ATPase. A computer-generated model of this region illustrates the possible involvement of the residues previously shown to affect SCH28080 inhibition (Cys813, Ile816, Thr823, Met334, Val337) and may predict other residues that line the SCH28080 binding vestibule in the E(2) conformation of the pump.

Amino Acid Sequence↗
PubMed2001

Use of a Shack-Hartmann aberrometer to assess the optical outcome of corneal transplantation in a keratoconic eye.

We report the optical outcome of corneal transplantation treatment on a keratoconic eye as measured with a Shack-Hartmann aberrometer, and we compare the results with the recovery of visual acuity after surgery. Before surgery, the naked keratoconic eye exhibited extremely large aberrations that could not be measured unless the patient wore a rigid gas-permeable contact lens. With the lens, the computed point-spread function of the eye was large and multimodal, and simulated retinal images confirmed the patient's subjective report of multiple, overlapping images. After full recovery from surgery, aberrations of the corrected eye were much smaller compared with the presurgical eye, which implied a more compact point-spread function and clearer retinal images. These optical changes were mirrored by an improvement in uncorrected visual acuity from 1.3 logarithm of the minimum angle of resolution (logMAR) before surgery to 0 logMAR with spectacle correction after full recovery. We conclude that the Shack-Hartmann aberrometer provides an objective, quantitative assessment of the optical outcome of penetrating keratoplasty that allows the clinician to measure retinal image quality objectively and to accurately simulate the complex visual distortions associated with keratoconus.

Cornea↗
PubMed2001

No more tours: how library tours of the past become today's celebrations.

In 1999, Northwestern University's Galter Health Sciences Library redesigned the library orientation program for first-year medical students. Surveys indicated tours were ineffective and students retained little of the information presented. Furthermore, the tour was not related to the student's curriculum and did not reinforce their learning objectives. As a replacement, the library staff developed a self-directed two-hour library open house. Stations throughout the library showcased the library staff, services, and resources, focusing on the first-year student curriculum. A follow-up survey found this redesign more useful and relevant to the students' course work, indicating libraries should be creating more interactive tours for students allowing them to learn actively.

Chicago↗
PubMed2000

Comparison of covalent with reversible inhibitor binding sites of the gastric H,K-ATPase by site-directed mutagenesis.

The gastric H,K-ATPase is covalently inhibited by substituted pyridyl-methylsulfinyl-benzimidazoles, such as omeprazole, that convert to thiophilic probes of luminally accessible cysteines in the acid space. The K(+) competitive inhibitor, SCH28080, prevented inhibition of acid transport by omeprazole. In stably expressing HEK293 cells, the benzimidazole-reactive cysteines, Cys-321 (transmembrane helix (TM) 3), Cys-813 and Cys-822 (TM5/6), and Cys-892 (TM7/8) were mutated to the amino acids found in the SCH28080-resistant Na,K-ATPase and kinetic parameters of H,K-ATPase activity analyzed. Mutations of Cys-822 and Cys-892 had insignificant effects on the K(i(app)), K(m(app)) or V(max), but mutations of Cys-813 to threonine and Cys-321 to alanine decreased the affinity for SCH28080. Mutation of Cys-321 to alanine produced mixed kinetics of inhibition, still with higher affinity for the cation-free form of phosphoenzyme. Since the phenylmethoxy ring of the imidazo-pyridine inhibitors binds to TM1/2, as shown by earlier photoaffinity studies, and the mutations in TM6 (Cys-813 --> Thr) as well as the end of TM3 (Cys-321 --> Ala) decrease the affinity for SCH28080, the TM1/2, TM3, and TM6 helices lie within approximately 16 A of each other based on the size of the active, extended conformation of SCH28080.

Anti-Ulcer Agents↗
PubMed2000

Review article: the control of gastric acid and Helicobacter pylori eradication.

This review focuses on the gastric acid pump as a therapeutic target for the control of acid secretion in peptic ulcer and gastro-oesophageal reflux disease. The mechanism of the proton pump inhibitors is discussed as well as their clinical use. The biology of Helicobacter pylori as a gastric denizen is then discussed, with special regard to its mechanisms of acid resistance. Here the properties of the products of the urease gene clusters, ureA, B and ureI, E, F, G and H are explored in order to explain the unique location of this pathogen. The dominant requirement for acid resistance is the presence of a proton gated urea transporter, UreI, which increases access of gastric juice urea to the intrabacterial urease 300-fold. This enables rapid and continuous buffering of the bacterial periplasm to approximately pH 6.0, allowing acid resistance and growth at acidic pH in the presence of 1 mM urea. A hypothesis for the basis of combination therapy for eradication is also presented.

Gastric Acid↗
PubMed2000

The Minnesota DARE PLUS Project: creating community partnerships to prevent drug use and violence.

The research community has criticized Drug Abuse Resistance Education (D.A.R.E.) because the extant literature indicates a lack of evidence that the elementary school program prevents drug use. Yet D.A.R.E. continues to be the most widely implemented drug use prevention program in the United States and has considerable community support. To date, the junior high D.A.R.E. program has not been evaluated. The Minnesota DARE PLUS Project is a randomized trial of 24 schools and communities. During 1999-2001, students in eight schools will receive the junior high D.A.R.E. curriculum in 7th grade; eight schools also will receive the curriculum as well as additional parent involvement, peer leadership, and community components in the 7th and 8th grades; and eight schools will serve as controls. This article describes the background and conceptualization, the curriculum and additional intervention components, and the evaluation methods of the DARE PLUS Project.

Adolescent↗
PubMed2000

Analysis of the membrane domain of the gastric H(+)/K(+)-ATPase.

A structure of the catalytic or alpha subunit of the H(+)/K(+)-ATPase, with ten transmembrane segments, and of the beta subunit, with a single such segment, was established using a combination of tryptic cleavage and peptide sequencing and in vitro translation. Sites at which covalent ligands bind to external surfaces were also defined by cleavage, separation and sequencing. Cys813 was found to be the common covalent binding site for all the substituted pyridyl methylsulfinyl benzimidazoles. The binding region of a K(+)-competitive reagent, the 1,2 &agr; -imidazo-pyridine SCH 28080, was defined by the kinetic effects of site-specific mutations. Amino acids substitutions in membrane-spanning segments M1, M3, M4 and M6 were found to influence the apparent inhibitor constant, K(i), to varying degrees, some having a large effect, some a moderate effect and some a slight effect, whereas some mutations had no effect. We interpret changes in K(i) without effects on the apparent Michaelis constant, K(m), as affecting SCH 28080 binding only. Mutation of Cys813 significantly affected the K(i) for SCH 28080, explaining the prevention of benzimidazole inhibition by the imidazo-pyridine.A model of the &agr; subunit was constructed with a vestibule on the luminal surface of the pump bounded by M1-M6 and containing the SCH 28080 binding region. The cation binding site is suggested to be more towards the cytoplasmic face of the enzyme's membrane domain. This model predicts the membrane peptide associations for the catalytic subunit. Biochemical and yeast two-hybrid methods place the beta subunit in association with M8, whereas similar methods place M5/6 in proximity to M9/10. These results, when combined with analysis of the two-dimensional crystals of the sarcoplasmic reticular Ca(2+) and Neurospora crassa H(+)-ATPases, provide the basis for a tentative model of the arrangement of the six core segments of the gastric H(+)/K(+)-ATPase.

Animals↗
PubMed1999

Isolation and analysis of amplified cDNA fragments during detection of unknown polymorphisms with temperature modulated heteroduplex chromatography.

A procedure for isolation of polymerase chain reaction (PCR) fragments from an automated system for DNA fragment analysis is described. The technique is used for screening of unknown mutations or polymorphisms. Fragments are isolated during the analysis from the system by an automated unit for high-throughput projects or manually when working with a few samples.

Chromatography↗
PubMed1996

The effect of intravesical mitomycin C on recurrence of newly diagnosed superficial bladder cancer: a further report with 7 years of follow up.

PURPOSE: We determined the role, if any, of 1 and 5 instillations of intravesical mitomycin C in the treatment of newly diagnosed superficial bladder cancer. MATERIALS AND METHODS: A multicenter randomized clinical trial was done involving 502 patients with newly diagnosed superficial bladder cancer. After complete transurethral resection patients with newly diagnosed superficial bladder cancer. After complete resection patients were randomized into 1 of 3 treatment arms: no further treatment, 1 instillation of mitomycin C at resection and 1 instillation at resection and at 3-month intervals for 1 year (total 5 instillations). The dose of mitomycin C used was 40 mg./40 ml. water. End points were interval to first superficial recurrence, recurrence rate (defined as the number of positive cystoscopies per year) and progression-free interval rate (progression defined as the development of muscle invasive or metastatic disease, or death from bladder cancer). RESULTS: After median followup of 7 years 1 and 5 instillations of mitomycin C resulted in decreased recurrence rates and increased recurrence-free interval. The benefit of mitomycin C was observed in patients at low, medium and high risk for subsequent recurrence. There was suggestive but not conclusive evidence that 5 instillations of mitomycin C offered a slight advantage over 1 instillation. CONCLUSIONS: Our analysis confirms the positive benefit of mitomycin C to decrease the number of subsequent recurrences and increase the recurrence-free interval.

Administration, Intravesical↗
PubMed1993

Membrane topology and omeprazole labeling of the gastric H+,K(+)-adenosinetriphosphatase.

The gastric H+,K(+)-ATPase is an alpha beta heterodimer with close homology to the Na+,K(+)-ATPase. Digestion of intact cytoplasmic-side-out vesicles at a trypsin to protein ratio of 1/4 removed most of the cytoplasmic protein, leaving membrane-spanning pairs in high yield. These were visualized on gels and poly(vinylidene difluoride) (PVDF) membranes by sodium dodecyl sulfate solubilization of the membrane-embedded segments and labeling of the cysteine residues with fluorescein maleimide prior to electrophoresis. The membrane-spanning residues of the alpha subunit were found between positions 104 and 162 (M1/M2), 291 and 358(M3/M4), 776 and 835 (M5/M6), and 853 and 946 (M7/M8). Although this method did not detect membrane retention of the hydrophobic sequences subsequent to position 946, it provided biochemical evidence for at least eight membrane segments in the catalytic subunit. Intact vesicles containing this enzyme transport acid in the presence of KCl, valinomycin, and MgATP. Omeprazole accumulates in these acidified vesicles and converts to a cationic sulfenamide. This forms disulfides with accessible cysteines. The reaction with this extracytoplasmic thiol reagent inhibits ATPase activity. Full inhibition was obtained with a stoichiometry of 2.2 mol of omeprazole bound/mg of protein. Only the alpha subunit was labeled. The cysteines reacting with omeprazole were defined by proteolytic cleavage of 3H- or 14C-omeprazole-labeled enzyme followed by peptide sequencing of fragments separated on tricine gradient gels and transferred to PVDF membranes. Tryptic digestion at a 1/40 trypsin to protein ratio in the presence of ligands that stabilize the E2P form of the enzyme produced two large fragments, one of 68 kDa stretching from Glu47 to probably Arg666 that contained minor labeling and the other of 333 kDa beginning at Ala671 and extending to probably Arg946 that contained greater than 85% of the label. Digestion of labeled vesicles at 1/75 or 1/4 trypsin to protein ratios gave radioactive patterns consistent with labeling at Cys813 and/or Cys822 and at Cys892 and/or Cys927 and/or Cys938. V8 protease digestion of the solubilized alpha subunit produced a fragment extending from Ser838 to possible Asp900 that was omeprazole-labeled, showing that Cys892 was labeled and Cys927 and Cys938 were not. Hence, omeprazole labels the H+,K(+)-ATPase at cysteines within the M5/M6 and M7/M8 regions of the alpha subunit, accounting for its inhibitory action in vivo and in vitro.

Adenosine Triphosphate↗
PubMed1992

Determination of the sidedness of the C-terminal region of the gastric H,K-ATPase alpha subunit.

It cannot be predicted from hydropathy analysis whether the C-terminal end of the alpha subunit of the gastric H,K-ATPase is cytoplasmic or extracytoplasmic. The sideness of the C-terminal amino acids was determined by taking advantage of the two C-terminal tyrosines in the primary sequence of the enzyme. Intact, cytoplasmic side out vesicles derived from hog gastric mucosa or detergent solubilized vesicles were iodinated by the lactoperoxidase method and then the C-terminal amino acids hydrolyzed by carboxypeptidase Y. The alpha and beta subunits were separated by SDS gel electrophoresis. The level of iodination of the alpha subunit following solubilization was about three fold greater than when intact vesicles were iodinated, and the beta subunit was iodinated only when solubilized enzyme was used. Carboxypeptidase Y removed 28 +/- 4% of the radioactivity from the alpha subunit iodinated in intact vesicles. These data are consistent with a cytoplasmic location of the C-terminal amino acids of the alpha subunit and with a mostly extracytoplasmic location of the amino acids of the beta subunit.

Animals↗
PubMed1992

Topology and sites in the H,K-ATPase.

Understanding the membrane topology of the EP-type pumps has been approached largely by analysis of hydrophobicity plots, which are confusing in the COOH-terminal third of the proteins. Each pair of predicted membrane-spanning segments with the extracytoplasmic loop contains at least one cysteine, allowing fluorescent labeling of these regions of the enzymes by cysteine reagents once the cytoplasmic domain has been removed. The membrane segment arrangement of the H,K and sr Ca ATPases was investigated by tryptic cleavage of intact cytoplasmic face-out vesicles. This was followed by fluorescein or coumarin maleimide labeling of the SDS solubilized residual membrane fragments, tricine gradient gel separation, and sequencing. The presence of four membrane-spanning pairs was demonstrated for the alpha subunit of the H,K-ATPase, with no membrane retention of H9 and H10, although H9 has four cysteines based on cDNA sequencing. A similar observation was made for the Ca pump, except that fluorescein-labeled H9 was detected in the membrane with a molecular weight of 4 kD, showing that cleavage had occurred at lys958 predicted to be extracytoplasmic in a 10 membrane segment model. It seems likely that for both these enzymes the membrane domain contains only 8 alpha helical spanning segments. Cleavage at ala236 in the beta subunit was found only in leaky, not in ion-tight vesicles, arguing for a single membrane segment in this subunit. In the H,K-ATPase additional evidence for the presence and arrangement of the first, third, and fourth pair of segments was obtained by labeling the intact enzyme with extracytoplasmic inhibitory reagents. The K competitive reagent, an imidazopyridine, MeDAZIP+, labeled the first pair of membrane segments. The acid-activated SH reagent class, the pyridinyl methyl sulfinyl benzimidazoles, labeled cysteines 813 and 822 in the M5/M6 region as well as cysteine 892 in the extracytoplasmic loop between M7 and M8. No labeling of the beta subunit was found, indicating the presence of three disulfide bonds in the extracytoplasmic domain of this subunit. Both sets of extracytoplasmic reagents are predicted to bind close to the fatty acid/phospholipid head group interface. Inhibition by these reagents shows that conformational changes are transmitted between cytoplasmic and extracytoplasmic domains.

Amino Acid Sequence↗
PubMed1992

Structural aspects of the gastric H,K-ATPase.

The gastric H,K-ATPase is an alpha, beta heterodimer. The large catalytic subunit is composed, in the case of the hog enzyme, of 1033 amino acids, whereas the beta subunit is composed of about 291 amino acids and is heavily glycosylated. The membrane topology of the alpha subunit is difficult to predict using hydropathy analysis. Tryptic hydrolysis of intact, inside out vesicles followed by cysteine labelling with fluorescein-5-maleimide provided experimental evidence for an 8 membrane spanning model for the alpha subunit, between residues 104 and 162 (M1/M2), 291 and 358 (M3/M4), 776 and 835 (M5/M6), and 853 and 946 (M7/M8). No evidence was found for a pair of segments (M9/M10) towards the C terminal end of the molecule, contrary to predictions for the Na,K- and Ca-ATPases. Iodination of intact vesicles followed by carboxypeptidase Y cleavage of the C terminal tyrosines showed that the C terminal end of the alpha subunit was cytoplasmic. The epitope for antibody 146 was extracytoplasmic and located between residues 871 to 874 between M7/M8. The binding site of the K competitive imidazo-pyridine, SCH28080, was to the extracytoplasmic loop between M1 and M2, whereas the binding of the covalent SH reagent generated from acid activation of omeprazole in acid transporting vesicles was to 2 cysteines at positions 813 (or 822) and 892 predicted to be in the extracytoplasmic loops connecting M5/M6 and M7/M8, respectively. The beta subunit was only hydrolysed in broken vesicles. A fragment beginning at position 236 was liberated under these conditions only in the presence of reducing agents, showing that cysteine 210 and 263 were disulfide linked.(ABSTRACT TRUNCATED AT 250 WORDS)

Amino Acid Sequence↗
PubMed1992

Chemomechanical coupling in the gastric H,K ATPase.

The gastric H,K ATPase is investigated in terms of its secondary structure by analysis of the binding sites of the extracytoplasmic inhibitors and by tryptic cleavage of intact, inside-out gastric vesicles. The inhibitors affect phosphorylation and other partial reactions of the ATPase that depend on cytoplasmic conformational changes. The K competitive imidazopyridine, SCH28080 binds to the first pair of transmembrane segments, M1/M2, probably at phe124 and asp136. Omeprazole which generates a cationic sulfenamide in acid spaces binds to either cys813 or cys822 at one site and cys892 at the other. These cysteines are located at the membrane spanning pairs, M5/M6 and at M7/M8. Tryptic cleavage of intact inside out vesicles followed by labelling with fluorescein-5-maleimide provides direct evidence for 8 membrane spanning segments between positions 104/162 (M1/M2), 291/358(M3/M4), 776/835 (M5/M6),853/946 (M7/M8). Evidence is lacking so far for M9/M10, postulated on the basis of hydrophobicity for the Ca ATPase. Conformational studies suggest that there is interaction between the cytoplasmic loop between M4 and M5 (ATP domain) and the extracytoplasmic domain of the enzyme at the inhibitor binding sites.

Adenosine Triphosphate↗
PubMed1991

Mammalian phosphorylating ion-motive ATPases.

The pumps discussed in this review are three members of the phosphorylating class of ion transport ATPases. They are the Na(+)-K(+)-, Ca(2+)- and H(+)-K(+)-ATPases. Recent work on their topology, possible transport mechanisms, ion-binding sites and role of the different subunits found for the Na(+)-K(+)- and H(+)-K(+)-ATPases is presented, with a suggestion of a unifying 10-membrane segment model for the catalytic subunit of this class of enzyme.

Amino Acid Sequence↗