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.

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gi 1907140931  67 LKCYNCLDPVSSCKINTTCSPNLDSCLYAVAG 98
Cdd:cd23554     1 LKCYNCPNPTSNCNTNVTCSSNLDACLIVKAG 32

extracellular domain (ECD) found in CD59 glycoprotein and similar proteins; CD59 (also called 1F5 antigen, or 20 kDa homologous restriction factor, or HRF-20, or MAC-inhibitory protein (MAC-IP), or MEM43 antigen, or membrane attack complex inhibition factor (MACIF), or membrane inhibitor of reactive lysis (MIRL), or protectin) is an LY-6-like protein expressed in human lymphoid cells and inhibits the action of the complement membrane attack complex (MAC) on homologous cells. It acts by binding to the C8 and/or C9 complements of the assembling MAC, thereby preventing incorporation of the multiple copies of C9 required for complete formation of the osmolytic pore. This inhibitor appears to be species-specific. CD59 is also involved in signal transduction for T-cell activation complexed to a protein tyrosine kinase. CD59 contains an extracellular domain (ECD) which belongs to Ly-6 antigen/uPA receptor-like (LU) superfamily and exhibits a snake toxin-like fold (also known as three-finger toxin/3FTx fold or three-fingered protein/TFP domain fold).

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gi 1907140931  67 LKCYNCLDPVSSCKINTTCSPNLDSCLYAVAG 98
Cdd:cd23554     1 LKCYNCPNPTSNCNTNVTCSSNLDACLIVKAG 32

extracellular domain (ECD) found in CD59 glycoprotein and similar proteins; CD59 (also called 1F5 antigen, or 20 kDa homologous restriction factor, or HRF-20, or MAC-inhibitory protein (MAC-IP), or MEM43 antigen, or membrane attack complex inhibition factor (MACIF), or membrane inhibitor of reactive lysis (MIRL), or protectin) is an LY-6-like protein expressed in human lymphoid cells and inhibits the action of the complement membrane attack complex (MAC) on homologous cells. It acts by binding to the C8 and/or C9 complements of the assembling MAC, thereby preventing incorporation of the multiple copies of C9 required for complete formation of the osmolytic pore. This inhibitor appears to be species-specific. CD59 is also involved in signal transduction for T-cell activation complexed to a protein tyrosine kinase. CD59 contains an extracellular domain (ECD) which belongs to Ly-6 antigen/uPA receptor-like (LU) superfamily and exhibits a snake toxin-like fold (also known as three-finger toxin/3FTx fold or three-fingered protein/TFP domain fold).

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                  ....*....|....*....|....*....|..
gi 1907140931  67 LKCYNCLDPVSSCKINTTCSPNLDSCLYAVAG 98
Cdd:cd23554     1 LKCYNCPNPTSNCNTNVTCSSNLDACLIVKAG 32