title: Human erythrocyte ankyrin, a cytoskeleton component, generates the p57 membrane proteinase which cleaves C3, the third component of complement.
abstract: Human erythrocytes express a p57 membrane serine proteinase which cleaves C3, the third component of complement. Amino acid analysis of the first 20 N-terminal residues of the purified p57 proteinase demonstrated 100% homology with residues 910-929 of erythrocyte ankyrin, a sequence localized in its Mr = 62 kDa fragment. Thus, we analyzed whether ankyrin could generate the p57 C3-cleaving activity. We demonstrate herein that: 1) anti-ankyrin antibodies react with purified p57 proteinase; 2) anti-p57 proteinase antibodies react with purified ankyrin but not with spectrin, another cytoskeleton component; 3) while purified ankyrin did not carry any detectable proteinase activity, limited proteolysis of ankyrin by immobilized chymotrypsin generated this C3-cleaving serine proteinase. Spectrin did not generate any C3-cleaving activity. This is the first demonstration that erythrocyte ankyrin could generate a proteinase activity, which in addition, cleaves specifically human C3.
authors.affiliation: Immunochimie des Régulations Cellulaires et des Interactions Virales, INSERM U.354, Hôpital Saint-Antoine, Paris, France.
authors.forename: J
authors.initials: J
authors.lastname: Hermann
authors.forename: M
authors.initials: M
authors.lastname: Barel
authors.forename: R
authors.initials: R
authors.lastname: Frade
mesh_terms: D000595:Amino Acid Sequence; D017487:Ankyrins / Q000276:immunology / Q000378:metabolism*; D003176:Complement C3 / Q000378:metabolism*; D003599:Cytoskeleton / Q000378:metabolism*; D000939:Epitopes; D004910:Erythrocyte Membrane / Q000201:enzymology / Q000378:metabolism*; D006801:Humans; D006868:Hydrolysis; D066298:In Vitro Techniques; D008969:Molecular Sequence Data; D017386:Sequence Homology, Amino Acid; D012697:Serine Endopeptidases / Q000737:chemistry / Q000276:immunology / Q000378:metabolism*
chemical_list: D017487:Ankyrins; D003176:Complement C3; D000939:Epitopes; D012697:Serine Endopeptidases; C090165:p57 serine proteinase