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).
Jiyao W et al.(2023). "The conserved domain database in 2023.",