The function of ENSG00000156398 (SFXN2, sideroflexin 2) is as follows. Mitochondrial amino-acid transporter that mediates transport of serine into mitochondria (PubMed:30442778). Involved in mitochondrial iron homeostasis by regulating heme biosynthesis (PubMed:30570704). {ECO:0000269|PubMed:30442778, ECO:0000269|PubMed:30570704}.