SFXN1 Gene – Sideroflexin 1: Function, Expression, Mutations & Disease

SFXN1 (Sideroflexin 1) encodes a mitochondrial inner membrane protein belonging to the sideroflexin family. It functions as a serine transporter, importing serine into mitochondria for one-carbon unit metabolism. SFXN1 is essential for mitochondrial folate-dependent serine catabolism, contributing to nucleotide synthesis and redox balance. The gene is broadly expressed, with highest levels in liver, kidney, and brain. Dysregulation of SFXN1 is implicated in cancer cell proliferation and neurological conditions.

Tissue Expression

Cell Line Expression

Hotspot Mutations

Mutation functional classification

• Mitochondrial one-carbon metabolism (serine catabolism)

• Folate cycle

• Serine biosynthesis and degradation

SFXN1 is a 322-amino acid mitochondrial inner membrane protein with six transmembrane domains. It mediates the import of serine into the mitochondrial matrix, where serine is converted to glycine and a one-carbon unit (formate) via the mitochondrial folate pathway. This process is critical for de novo purine and thymidine synthesis, as well as for maintaining cellular redox balance. SFXN1 is widely expressed and its upregulation in cancers supports rapid proliferation by enhancing nucleotide production.