Implications of amino acid compartmentation for the determination of rates of protein catabolism in livers in meal fed rats

Ea, Khairallah; Airhart, J; Mk, Bruno; Puchalsky, D; Khairallah, L

doi:10.1515/9783112650080-030

Cited by 6 publications

(1 citation statement)

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“…Such separation between a storage and a metabolically active pool often occurs in different eucaryotic cells. It was originally observed for amino acids in yeast cells (7, 31) and was described for Neurospora crassa (2,6,22), alkaloid-producing Penicillium cyclopium (16), plants (17), and, in a modified form, animal cells (5,9). However, the isolation of the storage pool is restricted so far to few examples (14,22,31).…”

Section: Discussionmentioning

confidence: 99%

Compartmentation of Uracil in Euglena gracilis

Wasternack

1983

Molecular and Cellular Biology

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Compartmentation of uracil in the flagellate Euglena gracilis was studied by tracer-kinetic experiments. Lag times in the equilibration of exogenously given and intracellularly present uracil before linear labeling of catabolic and anabolic products was determined to estimate the size of its metabolically active pool. This pool operates in the incorporation and degradation of uracil. There were the same lag times in forming both final products when measured in parallel and when measured after preloading with pyrimidines, in different cell strains, and under various environmental conditions. The amount of the metabolically active uracil pool, estimated as 11 pmol/10(7) heterotrophically growing cells, decreased to almost zero during light-induced RNA synthesis and could be changed by preloading with uracil or thymine. Besides this metabolic pool, cells may contain large amounts of uracil in a membrane-enclosed storage compartment (up to 12 nmol/10(7) cells). This is metabolically inert, but may be mobilized by nitrogen-carbon starvation. The role of uracil compartmentation in this metabolically flexible organism is discussed.

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