Bf. Lin et al., REGULATION OF FOLATE AND ONE-CARBON METABOLISM IN MAMMALIAN-CELLS .3.ROLE OF MITOCHONDRIAL FOLYLPOLY-GAMMA-GLUTAMATE SYNTHETASE, The Journal of biological chemistry, 268(29), 1993, pp. 21674-21679
Wild-type Chinese hamster ovary (CHO) cells and CHO cell transfectants
expressing human folylpoly-gamma-glutamate synthetase (FPGS) activity
contain mitochondrial FPGS activity of higher specific activity than
the cytosolic isozyme. Expression of mitochondrial FPGS activity is re
quired for folate accumulation by mitochondria. The mitochondrial fola
te pool in CHO cells is not in equilibrium with the cytosolic pool and
contains folylpolyglutamates of longer glutamate chain length than cy
tosolic folates. The inability of AUX-coli, a CHO cell expressing high
levels of Escherichia coli FPGS activity and containing pteroyltriglu
tamate, to support glycine synthesis is due to a lack of mitochondrial
FPGS activity. AUX-coli cells lack mitochondrial folate despite conta
ining high levels of cytosolic folate.