The NADP-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase is not expressed in Spodoptera frugiperda cells
The insect cell line derived from Spodoptera frugiperda (Sf9) does not express the activities of the trifunctional NADP-dependent methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase. The lack of synthetase activity was confirmed by the in...
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Veröffentlicht in: | The Journal of biological chemistry 1992-04, Vol.267 (12), p.8281-8285 |
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Sprache: | eng |
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Zusammenfassung: | The insect cell line derived from Spodoptera frugiperda (Sf9) does not express the activities of the trifunctional NADP-dependent
methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase-formyltetrahydrofolate synthetase. The lack
of synthetase activity was confirmed by the inability to incorporate radiolabeled formate into nucleotides. The cells express,
instead, a Mg2+ and NAD-dependent bifunctional methylenetetrahydrofolate dehydrogenase-methenyltetrahydrofolate cyclohydrolase
with properties similar to the enzyme found in the mitochondria of transformed mammalian cells. In contrast, the enzyme in
Sf9 cells is localized in the cytoplasm. Nutritional studies in defined medium with dialyzed serum demonstrated that the Sf9
cell does not required added purines or pyrimidines for growth. It is auxotrophic for cysteine and glycine; this latter requirement
is probably due to the absence of mitochondrial serine hydroxymethyltransferase. Incorporation of labeled glycine and serine
into DNA indicates that only serine is a source of one-carbon units. These results suggest that the mitochondria in Sf9 cells
do not play a major role in folate-mediated metabolism. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1016/S0021-9258(18)42439-8 |