Transport of dibasic amino acids by human erythrocytes

Gardner, Jerry D.; Levy, Alison

doi:10.1016/0026-0495(72)90054-6

Cited by 45 publications

(14 citation statements)

References 21 publications

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“…The failure of genes, which instruct important membrane events in the transepithelial absorption of nutrients, to be expressed in nonepithelial tissues, is not a new observation. The most recent examples are found in the fibroblast studies of Groth and Rosenberg (27) and in the erythrocyte studies of Gardner and Levy (28). The former found normal uptake of dibasic amino acids and tryptophan in the cultured skin fibroblasts from patients with Hartnup disease and cystinuria in whom there was unequivocal evidence for impaired intestinal and renal tubular absorption of the relevant amino acids.…”

Section: Discussionmentioning

confidence: 96%

Orthophosphate transport in the erythrocyte of normal subjects and of patients with X-linked hypophosphatemia.

Tenenhouse¹,

Scriver²

1975

J. Clin. Invest.

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A B S T R A C T We have examined the mechanism of TCA-soluble orthophosphate (P.) transfer across the membrane of mature human erythrocytes in normal subjects and in patients with X-linked hypophosphatemia (X-LH). The studies were carried out largely at pH 7.4 and 370C, in partial simulation of conditions in vivo. (a) At physiological concentrations (1-2 mM) P. enters the intact normal erythrocyte down its chemical gradient and under no conditions could we identify a steady-state trans-membrane gradient for Pi greater than 0.6. Calculations of the phosphate anion distribution ratio using the Nernst equation yield theoretical values that closely approximate observed values. (b) Glycolytic inhibitors have little effect on total entry of 'P, into erythrocytes but they do affect the intracellular distribution of P.. In the presence of iodoacetamide, label accumulates almost exclusively in the orthophosphate pool and less than 1% enters the organic phosphate pool. (c) Specific activity measurements in unblocked cells indicate that P. anion equilibrates first with its intracellular P. pool. These initial findings imply that neither group translocation, nor energy coupling, influence P. permeation into the human erythrocytes. (d) The relationship between 'P entry and extracellular P. concentration is parabolic in the presence of chloride, and linear in the presence of sulfate.

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Section: Discussionmentioning

confidence: 96%

Orthophosphate transport in the erythrocyte of normal subjects and of patients with X-linked hypophosphatemia.

Tenenhouse¹,

Scriver²

1975

J. Clin. Invest.

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“…Typical examples include: brain (Smith, 1967;La~nov~i & Brechtlov~i, 1971 ;Silverman, Knigge & Peck, 1972;Vahvelainen & Oja, 1972); choroid plexus (Lorenzo & Cutler, 1969;Coben, Cotlier, Beaty & Becker, 1971); diaphragm (Akedo & Christensen, 1962); chick heart (Guidotti, Borghetti, Gaja, Lo Reti &Fo~t, 1968); kidney (Segal & Crawhall, 1968); iris ciliary body (Coben, Cotlier, Beaty & Becker, 1970); ascites cells (Jacquez et al, 1970;Matthews, 1972); red cells (Eavenson &Christensen, 1967;Gardner &Levy, 1972); embryonic heart cells (Guidotti, Borghetti, Liineburg & Gazzola, 1971); and Streptococcusfaecalis . A similar component has been observed for other substrates; e.g., the uptake of uridine and adenosine by cultured hepatoma cells (Plagemann, 1970); and glucose by Pseudomonas aeruginosa (Eagon & Phibbs, 1971).…”

Section: The Unsaturable Componentmentioning

confidence: 98%

A comparison of the rate equations, kinetic parameters, and activation energies for the initial uptake ofl-lysine,l-valine, γ-aminobutyric acid, and α-aminoisobutyric acid by mouse brain slices

Cohen

1975

J. Membrain Biol.

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At substrate concentrations, in medium, of 0.2 to 20 mM and at temperatures of 25 and 37 degrees C, the initial concentrative influx of the amino acids L-lysine (30 and 37 degrees C), L-valine, and gamma-aminobutyric acid into incubated mouse-cerebrum slices follows the rate equation for the initial influx of alpha-aminoisobutyric acid (Cohen, J. Physiol. 228:105, 1973), v equals Vmax/(1+Kt/S)+kuS. Kinetic constants at 37 degrees C are: Vmax equals 0.089 mumoles/g final wet wt of slices, min, Kt equals 0.69 mM, ku equals 0.037 mumoles/g final wet wt, mM-substrate, min for L-lysine; Vmax equals 0.60, Kt equals 1.30, ku equals 0.067 for L-valine; and Vmax equals 1.71, Kt equals 1.58, ku equals 0.094 for gamma-aminobutyric acid. The linear term, kuS, is due to an unsaturable process of concentrative uptake, not diffusion. Comparison of temperature coefficients reveals a "reference" pattern for typical low affinity transport of amino acids into brain slices. Its characteristics are: Activation energies associated with Vmax and ku are in range 14 to 20 kcal/mole; K, varies only slightly with temperature, L-Lysine and alpha-aminoisobutyric acid fit this pattern; L-valine and gamma-aminobutyric acid deviate in part. The Akedo-Christensen plot (J. Biol. Chem. 237:118, 1962) does not distinguish between the rateequation v equals Vmax/(1+Kt/S)+kuS for saturable uptake plus first-order unsaturable concentrative uptake, and the rate equation v equals Vmax/(1 + Kt/S)+kd(S minus Si) for saturable uptake plus first-order nonconcentrative "passive diffusion".

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“…Five different transport systems have been described to account for the results of amino acid influx experiments on kinetics, substrate specificity and sodium dependence: an L-system for L-leucine, L-phenylalanine, L-methionine and L-valine (Winter & Christensen, 1964;Rosenberg & Rafaelsen, 1979;Young, Jones & Ellory, 1980), an Ly-system for Llysine, L-ornithine and L-arginine (Gardner & Levy, 1972;Young et al, 1980), a T-system for L-tryptophan and L-tyrosine (Rosenberg, Young & Ellory, 1980), an ASC-system for L-alanine and L-cysteine and a glycine transporting system (Ellory, Jones & Young, 1980). L-leucine transport has been characterized kinetically in some detail by Hoare (1972a, b).…”

Section: Cell (Erythrocyte) Kinetic Analysis Carrier Modelmentioning

confidence: 99%

l-leucine transport in human red blood cells: A detailed kinetic analysis

Rosenberg

1981

J. Membrain Biol.

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The kinetic properties of L-leucine transport across the human red blood cell membrane was analyzed according to the simple pore and carrier theory of Lieb and Stein (Biochim. Biophys. Acta, 1974, 373: 165-177 and 178-196) at 25 degrees C, pH 7.4. Several methods were used in order to obtain a thorough kinetic description of L-leucine transport. A rejection of the simple pore model was suggested from the result of zero-trans influx and zero-trans and equilibrium-exchange efflux experiments. Several predictions from the simple carrier model, based on the requirement of consistency among different kinetic parameters, were tested in infinite experiments, i.e. experiments performed at a high concentration of substrate at one of the faces of the membrane. The simple pore model was rejected, but no crucial evidence against a simple carrier model, which displays symmetric properties at 25 degrees C, was found in the concentration range considered (0.002-68 mM). The relative magnitudes of the rate constants of the translocation process are discussed, and it is concluded (a) that both the dissociation and translocation of carrier-complex is faster than the translocation of the empty carrier, (b) that no translocation step is rate determining, and (c) that the carrier-complex is equally distributed across the membrane at equilibrium. The present work provides a unique example of a carrier-mediated transport mechanism which displays symmetric properties. L-leucine transport in red blood cells may be a convenient system for studying molecular mechanisms of facilitated transport.

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Transport of dibasic amino acids by human erythrocytes

Cited by 45 publications

References 21 publications

Orthophosphate transport in the erythrocyte of normal subjects and of patients with X-linked hypophosphatemia.

Orthophosphate transport in the erythrocyte of normal subjects and of patients with X-linked hypophosphatemia.

A comparison of the rate equations, kinetic parameters, and activation energies for the initial uptake ofl-lysine,l-valine, γ-aminobutyric acid, and α-aminoisobutyric acid by mouse brain slices

l-leucine transport in human red blood cells: A detailed kinetic analysis

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