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three-fingered protein (TFP) fold found in Ly6/uPAR (LU) and snake toxin superfamily The LU (also known as Ly-6 antigen/uPA receptor)-like extracellular domain (ECD) occurs singly in GPI-linked cell-surface glycoproteins (Ly-6 family, CD59, thymocyte B cell antigen, Sgp-2) or as three-fold repeated domain in urokinase-type plasminogen activator receptor. It is a structural domain involved in protein-protein interactions, tolerating an unusual degree of variation and binding with high specificity to a broad spectrum of targets. The snake toxin domain is present in short and long neurotoxins, cytotoxins, and short toxins, and in other miscellaneous venom peptides. The toxin acts by binding to the nicotinic acetylcholine receptors in the postsynaptic membrane of skeletal muscles and preventing the binding of acetylcholine, thereby blocking the excitation of muscles. Both the LU-like ECD and the snake toxin domain belong to three-fingered protein (TFP) fold, which is characterized by containing 70 to 100 amino acids including eight to ten cysteine residues spaced at conserved distances. |
Jiyao W et al.(2023). "The conserved domain database in 2023.",