Identity of a peptide domain of human C9 that is bound by the cell-surface complement inhibitor, CD59.

摘要: Abstract The CD59 antigen is a plasma membrane glycoprotein that serves as an inhibitor of the C5b-9 complex complement. This inhibitory activity appears related to capacity bind with high affinity sites are nascently exposed in alpha-chain subunit human C8, well within C9b domain (amino acid residues 245-538) C9, during assembly on target (Ninomiya, H., and Sims, P. J. (1992) Biol. Chem. 267, 13675-13680). binding site C9 was first investigated by N-terminal sequencing CD59-binding peptides generated limited digest isolated domain. These experiments revealed 17-kDa fragment (starting at residue Thr-320) retained for CD59, suggesting possibility localizing mapping small C9-derived peptides. Peptides spanning entire sequence were expressed Escherichia coli then probed CD59. bound specifically all starting 359 C termini extending beyond 411. Little no observed various started C-terminal or truncated Affinity-purified antibody against 320-411 inhibited > 50% completely its specific detected restricted putative hinge (residues 245-271). results indicate located between 320 411 polypeptide suggest this principally determined 359-411.