TSTA3 Human

Tissue Specific Transplantation Antigen P35B, also known as TSTA3 or GDP-4-keto-6-deoxy-D-mannose epimerase/reductase, is a crucial enzyme in the biosynthesis of GDP-L-fucose. This enzyme plays a significant role in various biological processes, including immune response, cell cycle regulation, and glycosylation.

TSTA3 is a NADP(H)-binding protein that catalyzes the two-step epimerase and reductase reactions in GDP-D-mannose metabolism. Specifically, it converts GDP-4-keto-6-D-deoxymannose to GDP-L-fucose . This conversion is essential for the production of L-fucose, a sugar that is widely distributed in nature and is a component of bacterial, plant, and animal oligo- and polysaccharides .

The enzyme’s activity is crucial for the de novo pathway of GDP-L-fucose biosynthesis, which starts from GDP-D-mannose . L-fucose is inserted into glycoconjugates by the action of several fucosyltransferases that use GDP-L-fucose as a substrate. This process is vital for the proper functioning of various cellular activities, including cell-cell adhesion, signaling, and immune response .

TSTA3 has been identified as a significant low-expression gene in non-tumor hepatitis/cirrhotic tissues (HBV or HCV infection) compared to high-expression human hepatocellular carcinoma (HCC) . This differential expression suggests that TSTA3 may play a role in the progression of liver diseases and could be a potential biomarker for HCC.

Recent studies have shown that TSTA3-activated networks enhance the regulation of apoptosis, cyclin-dependent protein kinase activity, cell migration, and various other cellular processes . Understanding the role of TSTA3 in these pathways can provide insights into its potential therapeutic applications, especially in liver diseases and cancer.