Function: Serine palmitoyltransferase (SPT). The heterodimer formed with LCB1/SPTLC1 constitutes the catalytic core. The composition of the serine palmitoyltransferase (SPT) complex determines the substrate preference. The SPTLC1-SPTLC2-SPTSSA complex shows a strong preference for C16-CoA substrate, while the SPTLC1-SPTLC2-SPTSSB complex displays a preference for C18-CoA substrate. Ref.8 Ref.9
Catalytic activity: Palmitoyl-CoA + L-serine = CoA + 3-dehydro-D-sphinganine + CO2. Ref.8
Cofactor: Pyridoxal phosphate
By similarity.
Pathway: Lipid metabolism; sphingolipid metabolism.
Subunit structure: Heterodimer with SPTLC1. Component of the serine palmitoyltransferase (SPT) complex, composed of LCB1/SPTLC1, LCB2 (SPTLC2 or SPTLC3) and ssPT (SPTSSA and SPTSSB). Ref.8
Subcellular location: Endoplasmic reticulum membrane; Single-pass membrane protein
By similarity.
Tissue specificity: Widely expressed. Ref.7
Involvement in disease: Hereditary sensory and autonomic neuropathy 1C (HSAN1C) [MIM:613640]: A form of hereditary sensory and autonomic neuropathy, a genetically and clinically heterogeneous group of disorders characterized by degeneration of dorsal root and autonomic ganglion cells, and by prominent sensory abnormalities with a variable degree of motor and autonomic dysfunction. The neurological phenotype is often complicated by severe infections, osteomyelitis, and amputations. HSAN1C symptoms include loss of touch and vibration in the feet, dysesthesia and severe panmodal sensory loss in the upper and lower limbs, distal lower limb sensory loss with ulceration and osteomyelitis, and distal muscle weakness.Note: The disease is caused by mutations affecting the gene represented in this entry. SPTLC2 disease mutations cause a shift in the substrate specificity of SPT resulting in the alternative use of L-alanine and L-glycine over its canonical substrate L-serine. This leads to the production of 1-deoxysphingolipids that cannot be correctly metabolized (Ref.11). Ref.9 Ref.11
Sequence similarities: Belongs to the class-II pyridoxal-phosphate-dependent aminotransferase family.
Sequence caution: The sequence BAA25452.2 differs from that shown. Reason: Erroneous initiation.
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