6ljp | pdb_00006ljp
Crystal structure of human galectin-16
Structural highlights
Function[LEG16_HUMAN] Binds lactose with high affinity. Strong inducer of T-cell apoptosis.[1] Publication Abstract from PubMedBACKGROUND: The structure of human galectin-16 (Gal-16) has yet to be solved, and its function has remained elusive. METHODS: X-ray crystallography was used to determine the atomic structures of Gal-16 and two of its mutants. The Gal-16 oligomer state was investigated by gel filtration, its hemagglutination activity was determined along with its ability to bind lactose using ITC. The cellular distribution of EGFP-tagged Gal-16 in various cell lines was also investigated, and the interaction between Gal-16 and c-Rel was assessed by pull-down studies, microscale thermophoresis and immunofluorescence. RESULTS: Unlike other galectins, Gal-16 lacks the ability to bind the beta-galactoside lactose. Lactose binding could be regained by replacing an arginine (Arg55) with asparagine, as shown in the crystal structures of two lactose-loaded Gal-16 mutants (R55N and R55N/H57R). Gal-16 was also shown to be monomeric by gel filtration, as well as in crystal structures. Thus, this galectin could not induce erythrocyte agglutination. EGFP-tagged Gal-16 was found to be localized mostly in the nucleus of various cell types, and can interact with c-Rel, a member of NF-kappaB family. CONCLUSIONS: Gal-16 exists as a monomer and its ligand binding is significantly different from that of other prototype galectins, suggesting that it has a novel function(s). The interaction between Gal-16 and c-Rel indicates that Gal-16 may regulate signal transduction pathways via the c-Rel hub in B or T cells at the maternal-fetal interface. GENERAL SIGNIFICANCE: The present study lays the foundation for further studies into the cellular and physiological functions of Gal-16. Human galectin-16 has a pseudo ligand binding site and plays a role in regulating c-Rel-mediated lymphocyte activity.,Si Y, Yao Y, Jaramillo Ayala G, Li X, Han Q, Zhang W, Xu X, Tai G, Mayo KH, Zhou Y, Su J Biochim Biophys Acta Gen Subj. 2020 Oct 2;1865(1):129755. doi:, 10.1016/j.bbagen.2020.129755. PMID:33011338[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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