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Effect of the sugar chain of soluble recombinant CD59 on complement inhibitory activity
Author(s) -
Suzuki Hiroshi,
Yamaji Noboru,
Egashira Akira,
Yasunaga Kunio,
Sugita Yuji,
Masuho Yasuhiko
Publication year - 1996
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(96)01340-3
Subject(s) - recombinant dna , chemistry , sugar , inhibitory postsynaptic potential , cd59 , biochemistry , complement (music) , complement system , biology , immunology , endocrinology , antibody , gene , phenotype , complementation
A soluble recombinant CD59#77 (rCD59#77), consisting of 77 amino acids starting from the N terminus of membrane‐bound CD59, was prepared using a gene expression system in CHO cells. The rCD59#77 preparation was composed of glycosylated and non‐glycosylated forms (G and NG forms). Unexpectedly, NG form was 7 times more potent than G form in complement inhibitory activity. Postulating that sialic acids on G‐form molecules make it difficult for rCD59#77 to access nascent membrane attack complexes on the cell surface, the sialic acids were removed by neuraminidase treatment. However, the inhibitory activity was not changed. Next, one of two putative N‐glycosylation sites was mutated by substituting Gln 18 for Asn 18 . The mutant, designated rCD59#77(N/Q), had no sugar moiety and was as active as the NG form of rCD59#77. These results suggest that the bulky sugar moiety at Asn 18 is not necessary for the complement‐inhibitory activity of rCD59 and actually hampers that function.