Transport Across Cell Membranes

Whittam, R.; Wheeler, Kenneth P.

doi:10.1146/annurev.ph.32.030170.000321

Cited by 287 publications

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“…If the phosphatase activity is a manifestation of the K+-dependent dephosphorylation step in the complete ATPase reaction, then the added phospholipid must act somewhere between phosphorylation and dephosphorylation. Alternatively, the phosphatase activity must be regarded as being either separate from the ATPase activity, which seems unlikely in view of all the evidence available (see Whittam & Wheeler, 1970), or something different from a partial reaction of the ATPase. Since there is currently some dispute about the exact number and forms of phosphorylated intermediates in the overall reaction (Fukushima & Tonomura, 1973), the situation is perhaps best summarized thus:…”

Section: Discussionmentioning

confidence: 99%

“…Since the phosphorylation reaction that seems to be part of the complete ATPase reaction sequence is Na+-dependent (see Whittam & Wheeler, 1970) it was important to check the effect of Na+ concentration on the phosphorylation of these lipid-depleted enzymes. Fig.…”

Section: Time-course Of Hydrolysis and Phosphorylationmentioning

confidence: 99%

“…Thus a typical preparation after Lubrol extraction has a specific (Na++K+)-dependent ATPase activity amounting to only 5% of the original, whereas its specific K+-dependent phosphatase activity is still around 50% . Since the K+-dependent phosphatase activity is commonly thought to represent the last step of the complete ATPase reaction (see Whittam & Wheeler, 1970), these Lubrol-treated preparations appear to be very suitable for studying the partial reactions of the ATPase system. We have, therefore, compared the phosphorylation and dephosphorylation steps in the original, the lipid-depleted and the reactivated ATPase preparations, with the use of y-32P-labelled ATP for phosphorylation and pure phosphatidylserine for reactivation.…”

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confidence: 99%

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Role of phospholipid in the intermediate steps of the sodium-plus-potassium ion-dependent adenosine triphosphatase reaction

Wheeler

1975

Biochemical Journal

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Section: Discussionmentioning

confidence: 99%

Section: Time-course Of Hydrolysis and Phosphorylationmentioning

confidence: 99%

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Role of phospholipid in the intermediate steps of the sodium-plus-potassium ion-dependent adenosine triphosphatase reaction

Wheeler

1975

Biochemical Journal

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“…The over-all splitting of ATP by the sodium pump occurs in two stagesa sodium-dependent transfer of the terminal phosphate of ATP to protein and a potassium-dependent hydrolysis of this intermediate. The hydrolysis of p-nitrophenylphosphate (pNPP) resembles that of the intermediate in requiring potassium and in being inhibited by ouabain (see Whittam & Wheeler, 1970). Recent work showed that pNPP hydrolysis was markedly sensitive to the electrolyte concentration (Cotterrell & Whittam, 1972), and 10-3 35P PROCEEDINGS OF THE it was therefore necessary to see whether the natural phosphoprotein intermediate was similarly influenced by the ionic strength.…”

Section: Pmentioning

confidence: 99%

Communications

1973

The Journal of Physiology

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6PAPROCEEDINGS OF THE digital computers have eliminated the need for this intermediate step of data preparation and, leaving aside the question of cost and the time spent in programming, have made it possible to view spectra within a few seconds.Recently, special purpose analysers have become available which are even faster and require no programming. The demonstration is intended to show the advantages of one type of instrument (SAI-51A, Signal Analysis Industries Corp., New York) in the analysis of physiological muscle tremor. The particular feature of this intrument is that it uses digital sampling combined with some analogue processing. This results in such an increase in speed that it is possible to display the spectrum apparently continuously updated. The examination of signals in the frequency domain now becomes almost as direct as their usual display in the time domain. The value of this has already become evident, as will be demonstrated, in gaining some insight into the origin ofthe [8][9][10] Hz peak, which can be seen in the frequency spectrum of muscle tremor recorded during the maintenance of steady voluntary isometric contractions.

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“…RHR cell membrane is of considerable interest in connection with osmoregulation in the kidney cells. Present detailed knowledge concerning membrane transport has been obtained mainly in red cells, squid axon and muscle cells (2). It is clear that cells in most tissues have some forms of the Na pump.…”

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Effect of Ouabain on the Hyperosmolarity Tolerant Cells from Rat Kidney

Sato

Ozawa

1977

Japanese Journal of Pharmacology

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In a previous paper, we reported that the cell line (RHR cells) can survive in hypertonic culture media isolated from the rat kidney (1). Similar hyperosmolarity tolerant cells can be found specifically in the kidneys and such are capable of producing a well-concentrated urine. We have not been able to demonstrate such cells in other organs (unpublished work). RHR cells were grown in plastic Petri dishes (Falcon, 10 cm diameter) or culture flasks (Ikemoto, TD-15) with Ham's F12 medium supplemented with 30% calf serum, 50 U/ml penicillin G and 50 yg/ml streptomycin, in a humidified atmosphere of 3 % C02-97 % air at 37'C for 7 days until a confluent monolayer was established. The medium was then replaced with a hyperosmotic one prepared by addition of NaCl 12.9 g/1 to Ham's F12 medium to give a final osmolarity of approx. 600 mOsmole/ l . Forty-eight hours later ouabain (Merk) was added to the medium and the effect of this agent on cell proliferation was investigated over the dose range of 5 x 10_1 M to 10-s M (Table 1). At the dose of 10-s M, there was stimulation of growth during the 48 hr observation period. On the other hand, with a dose of 10-5 M, the viable cell number decreased to about 24 % of control. These biphasic effects About 2 x 104 cells in 1.5 ml hyperosmotic culture medium were implanted in a series of replicate culture flasks. Ouabain was administered on the 7th day. The number of viable cell nuclei was counted by hematocytometer 2 days after administration (3). The values represent mean±standard error obtained 5 replicate cultures.

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Transport Across Cell Membranes

Cited by 287 publications

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Role of phospholipid in the intermediate steps of the sodium-plus-potassium ion-dependent adenosine triphosphatase reaction

Role of phospholipid in the intermediate steps of the sodium-plus-potassium ion-dependent adenosine triphosphatase reaction

Communications

Effect of Ouabain on the Hyperosmolarity Tolerant Cells from Rat Kidney

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