Subcellular distribution of thiamine pyrophosphokinase activity in rat liver and erythrocytes

Deus, B.; Blum, Hubert E.

doi:10.1016/0005-2736(70)90229-4

Cited by 30 publications

(24 citation statements)

References 11 publications

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“…The lack of the specific component of thiamine transport in TRMA patients could alter considerably the cellular exchanges and absorption of thiamine and determine a state of vitamin deficiency, at least when food is the only source of thiamine intake. This condition in TRMA patients is worsened by the decreased level of TPKase, an exclusively cytoplasmic enzyme (Deus and Blum, 1970;Komai et al, 1974;Cusaro et al, 1977) that is necessary for the production of TPP, the important coenzymatic form of T which allows concentration and accumulation of the vitamin in tissues by metabolic trapping. While thiamine crosses cell membranes, thiamine phosphates do not.…”

Section: Discussionmentioning

confidence: 96%

Thiamine transport by erythrocytes and ghosts in thiamine‐responsive megaloblastic anaemia

Rindi

Casirola

Poggi

et al. 1991

J of Inher Metab Disea

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A 9-year study of thiamine metabolism and cellular transport was performed in two patients with thiamine-responsive megaloblastic anaemia associated with diabetes mellitus and sensorineural deafness, in their relatives, and in age-matched controls from the same area. The ratios between the content of thiamine and that of its phosphoesters in erythrocytes were within the normal range, whereas the absolute values of thiamine and thiamine compounds were reduced by about 40% as compared to controls. Thiamine pyrophosphokinase activity was about 30% lower than in controls. Thiamine treatment restored the levels of thiamine and thiamine compounds to normal values, whereas kinase was unaffected. Both the saturable (specific, predominant at low, less than 2 mumol/L, physiological concentrations of thiamine) and the non-saturable component of thiamine transport were investigated. Erythrocytes and ghosts from patients exhibited no saturable component, this abnormality being specific for the patients and not shared by their parents. It is concluded that the cells from thiamine-responsive megaloblastic anaemia patients contain low levels of thiamine compounds, probably due to their inability to take up and retain physiological concentrations of thiamine, as a result of the lack of the saturable, specific component of transport and reduced thiamine pyrophosphokinase.

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Section: Discussionmentioning

confidence: 96%

Thiamine transport by erythrocytes and ghosts in thiamine‐responsive megaloblastic anaemia

Rindi

Casirola

Poggi

et al. 1991

J of Inher Metab Disea

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“…Mammalian and yeast TPKs are reportedly cytosolic (Yoshioka 1984), but the presence of two redundant TPKs in Arabidopsis could be justified if the two proteins were differentially targeted to plastid and mitochondrial compartments to activate thiamin for TPP requiring enzymes within these organelles. However, this hypothesis is unlikely because no TPK activity was detected in rat liver mitochondria (Barile et al 1986;Deus and Blum 1970;Voskoboev and Averin 1981) and TPP uptake into rat liver mitochondria follows saturation kinetics (Barile et al 1990) suggesting that TPP is translocated from the cytosol to the mitochondria through protein transporters. In fact this was recently confirmed when a TPP mitochondrial transporter was identified in yeast (Marobbio et al 2002).…”

Section: Subcellular Localization Of Attpksmentioning

confidence: 94%

“…The fact that both AtTPKs are apparently targeted to the cytosol, like the mammalian and yeast TPKs (Barile et al 1990;Bettendorff 1995;Hohmann and Meacock 1998;Yoshioka 1984), implies that intracellular transport of TPP in plants must be similar to that of microorganisms and mammals. In addition to cytosolic enzymes, several mitochondrial and plastidial enzymes also require TPP for function, but due to its polar nature, TPP requires protein transporters for organellar import (Barile et al 1986;Deus and Blum 1970;Voskoboev and Averin 1981). To date, the yeast Tpc1p transporter is the only mitochondrial TPP transporter that has been identified (Marobbio et al 2002).…”

Section: Subcellular Localization Of Attpksmentioning

confidence: 97%

Thiamin pyrophosphokinase is required for thiamin cofactor activation in Arabidopsis

et al. 2007

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Thiamin pyrophosphate (TPP) is an essential enzyme cofactor required for the viability of all organisms. Whether derived from exogenous sources or through de novo synthesis, thiamin must be pyrophosphorylated for cofactor activation. The enzyme thiamin pyrophosphokinase (TPK) catalyzes the conversion of free thiamin to TPP in plants and other eukaryotic organisms and is central to thiamin cofactor activation. While TPK activity has been observed in a number of plant species, the corresponding gene/protein has until now not been identified or characterized for its role in thiamin metabolism. Here we report the functional identification of two Arabidopsis TPK genes, AtTPK1 and AtTPK2 and the enzymatic characterization of the corresponding proteins. AtTPK1 and AtTPK2 are biochemically redundant cytosolic proteins that are similarly expressed throughout different plant tissues. The essential nature of TPKs in plant metabolism is reflected in the observation that while single gene knockouts of either AtTPK1 or AtTPK2 were viable, the double mutant possessed a seedling lethal phenotype. HPLC analysis revealed the double mutant is nearly devoid of TPP and instead accumulates the precursor of the TPK reaction, free thiamin. These results suggest that TPK activity provides the sole mechanism by which exogenous and de novo derived thiamin is converted to the enzyme cofactor TPP.

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“…In rat erythrocytes, thiamin may bind to proteins (Voskoboyev & Averin, 1983) and may be phosphorylated intracellularly to thiamin-pyrophosphate by a thiamin-pyrophosphokinase which is present exclusively in the cytoplasm (Smits & Florijn, 1950;Deus & Blum, 1970). Since both events may influence the rate of thiamin uptake in humans as well, we also investigated thiamin phosphorylation by determining erythrocyte thiamin phosphate content after incubation, as well as thiamin binding in both erythrocytes and ghosts by using a microdialysis procedure.…”

Section: Introductionmentioning

confidence: 99%

Thiamin transport by human erythrocytes and ghosts

et al. 1990

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Thiamin transport in human erythrocytes and resealed pink ghosts was evaluated by incubating both preparations at 37 or 20 degrees C in the presence of [3H]-thiamin of high specific activity. The rate of uptake was consistently higher in erythrocytes than in ghosts. In both preparations, the time course of uptake was independent from the presence of Na+ and did not reach equilibrium after 60 min incubation. At concentrations below 0.5 microM and at 37 degrees C, thiamin was taken up predominantly by a saturable mechanism in both erythrocytes and ghosts. Apparent kinetic constants were: for erythrocytes, Km = 0.12, 0.11 and 0.10 microM and Jmax = 0.01, 0.02 and 0.03 pmol.microliter-1 intracellular water after 3, 15, and 30 min incubation times, respectively; for ghosts, Km = 0.16 and 0.51 microM and Jmax = 0.01 and 0.04 pmol.microliter-1 intracellular water after 15 and 30 min incubation times, respectively. At 20 degrees C, the saturable component disappeared in both preparations. Erythrocyte thiamin transport was not influenced by the presence of D-glucose or metabolic inhibitors. In both preparations, thiamin transport was inhibited competitively by unlabeled thiamin, pyrithiamin, amprolium and, to a lesser extent, oxythiamin, the inhibiting effect being always more marked in erythrocytes than in ghosts. Only approximately 20% of the thiamin taken up by erythrocytes was protein- (probably membrane-) bound. A similar proportion was esterified to thiamin pyrophosphate. Separate experiments using valinomycin and SCN- showed that the transport of thiamin, which is a cation at pH 7.4, is unaffected by changes in membrane potential in both preparations.

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Subcellular distribution of thiamine pyrophosphokinase activity in rat liver and erythrocytes

Cited by 30 publications

References 11 publications

Thiamine transport by erythrocytes and ghosts in thiamine‐responsive megaloblastic anaemia

Thiamine transport by erythrocytes and ghosts in thiamine‐responsive megaloblastic anaemia

Thiamin pyrophosphokinase is required for thiamin cofactor activation in Arabidopsis

Thiamin transport by human erythrocytes and ghosts

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