SPTSSA

Component of the serine palmitoyltransferase multisubunit enzyme (SPT) that catalyzes the initial and rate-limiting step in sphingolipid biosynthesis by condensing L-serine and activated acyl-CoA (most commonly palmitoyl-CoA) to form long-chain bases. The SPT complex is composed of SPTLC1, SPTLC2 or SPTLC3 and SPTSSA or SPTSSB. Within this complex, the heterodimer consisting of SPTLC1 and SPTLC2/SPTLC3 forms the catalytic core. Within the SPT complex, SPTSSA stimulates the catalytic activity and plays a role in substrate specificity, which depends upon the overall complex composition. The SPTLC1-SPTLC2-SPTSSA complex shows a strong preference for C16-CoA substrate, while the SPTLC1-SPTLC3-SPTSSA isozyme uses both C14-CoA and C16-CoA as substrates, with a slight preference for C14-CoA. Independently of its action as a SPT component, may be involved in MBOAT7 localization to mitochondria-associated membranes, a membrane bridge between the endoplasmic reticulum and mitochondria, may hence affect MBOAT7-catalyzed incorporation of arachidonic acid into phosphatidylinositol..

Function from UniProtKB (Q969W0), read 2026-09-23. CC BY 4.0.