Serine palmitoyltransferase small subunit A (SPTSSA)

Serine palmitoyltransferase small subunit A (SPTSSA) is a small regulatory membrane subunit of the **serine palmitoyltransferase (SPT) complex**, which catalyzes the initial and rate-limiting step in sphingolipid biosynthesis by the condensation of L-serine with acyl-CoA (typically palmitoyl-CoA)[2][3][5]. As part of the SPT multisubunit enzyme, SPTSSA does not have catalytic activity itself but stimulates and modulates SPT activity and acyl-CoA substrate selectivity by interacting with the core catalytic subunits, SPTLC1, SPTLC2, and/or SPTLC3[2][1][3]. SPTSSA is essential for full SPT activity, and genetic variants in SPTSSA can disrupt sphingolipid homeostasis, resulting in neurological disease phenotypes with complex presentations[5]. It is a single-pass transmembrane protein localized to the endoplasmic reticulum membrane and functions both in enzyme activation and in feedback inhibition mechanisms working with ORMDL proteins[1][2][5]. There are no direct drug modulators of SPTSSA described, but disruption of SPTSSA function alters sphingolipid levels and cellular lipid regulation, with consequences for inherited and acquired neurological diseases[5].

Other names

C14orf147SSSPTAssSPTaSmall subunit of serine palmitoyltransferase ASPG90ASPG90B