Mitochondrial serine transporter that mediates transport of serine into mitochondria, an important step of the one-carbon metabolism pathway. Mitochondrial serine is converted to glycine and formate, which then exits to the cytosol where it is used to generate the charged folates that serve as one-carbon donors.,SFXN3,BA108L7.2,SFX3,Signal Transduction,Endocrine & Metabolism,Mitochondrial metabolism,Mitochondrial markers,SFXN3