Retrovirally mediated complementation of the glyB phenotype - Cloning of ahuman gene encoding the carrier for entry of folates into mitochondria

The transduction of a human placental cDNA retroviral library into glyB cel ls, a Chinese hamster ovary RI subline that is deficient in the transport o f folates into mitochondria, resulted in the complementation of glycine aux otrophy of these cells. A 2.6-kilobase pair cDNA insert flanked by retrovir al sequences had integrated into genomic DNA in rescued cells. An open read ing frame in this cDNA encoded a 35-kDa protein homologous to several inner mitochondrial wall transporters for intermediate metabolites. The subclone d cDNA complemented the glycine auxotrophy of glyB cells and reinstated fol ate accumulation in the mitochondria of transfected cells, The human origin , chromosomal location, and intron-exon organization of the isolated mitoch ondrial folate transporter gene were deduced from the expressed sequence ta g database and human genome project data.