SHMT1 (Serine Hydroxymethyltransferase 1): SHMT1 is an enzyme that catalyzes the conversion of serine and tetrahydrofolate into glycine and methylenetetrahydrofolate. This process is essential for nucleotide synthesis and methylation reactions, which support DNA replication and repair. SHMT1 plays a key role in cell growth and genetic stability, and its activity in folate metabolism is linked to cancer risk and neurological disorders.