Recombinant Xenopus tropicalis Serine palmitoyltransferase small subunit B (sptssb)
Description
Protein Structure and Function
sptssb is a small subunit of the SPT holoenzyme, which typically comprises two large subunits (SPTLC1/2) and a small subunit (sptssa or sptssb). In Xenopus tropicalis, the recombinant sptssb protein has the following characteristics:
The protein stimulates SPT activity by altering substrate affinity and specificity, influencing the chain length of sphingolipid long-chain bases (LCBs) .
Biochemical Properties and Enzymatic Activity
sptssb modulates SPT activity by interacting with large subunits to regulate substrate binding. Key findings include:
Enzyme Kinetics
In Xenopus tropicalis and other models, sptssb mutations (e.g., Stellar in mice) increase SPT’s affinity for C18 fatty acyl-CoA substrates, elevating C20 LCB production . This gain-of-function effect is critical for studying sphingolipid homeostasis.
| Parameter | Wild-Type SPT | Mutant SPT (Stellar) | Source |
|---|---|---|---|
| Kₘ (C18 substrate) | Higher | 50% lower (higher affinity) | |
| Vₘₐₓ | Basal activity | Slightly increased |
Research Applications
The recombinant sptssb is used in:
Sphingolipid Metabolism Studies
-
C20 LCB Production: Mutations in sptssb elevate C20 sphingosine and ceramides, linked to neurodegeneration and protein misfolding in mice .
-
Cancer Research: SPTSSB upregulation in prostate cancer (PCa) cells after anti-androgen therapy suggests its role in de novo sphingolipid synthesis and therapeutic resistance .
Cell Line Development
sptssb-expressing Xenopus cell lines (e.g., XTN-6, XTN-8) enable studies of sphingolipid pathways in developmental biology and disease modeling .
Neurodegeneration and Sphingolipid Imbalance
-
The Stellar mutation in mice increases C20 LCBs, causing axon degeneration and ubiquitinated protein accumulation .
-
Elevated C20 ceramides disrupt membrane integrity and protein homeostasis .
Cancer Metabolism
-
SPTSSB knockdown reduces de novo sphingolipid synthesis in AR-negative prostate cancer cells, enhancing therapeutic efficacy .
Developmental Biology
Product Specs
Note: We prioritize shipping the format currently in stock. However, if you have specific format requirements, please indicate them when placing the order. We will accommodate your needs to the best of our ability.
Note: All proteins are shipped with standard blue ice packs. If you require dry ice shipping, please contact us in advance, as additional fees will apply.
Generally, the shelf life of liquid form is 6 months at -20°C/-80°C. The shelf life of lyophilized form is 12 months at -20°C/-80°C.
