Cfi

Complement factor I

604 amino acids

Trypsin-like serine protease that plays an essential role in regulating the immune response by controlling all complement pathways. Inhibits these pathways by cleaving three peptide bonds in the alpha-chain of C3b and two bonds in the alpha-chain of C4b thereby inactivating these proteins. Essential cofactors for these reactions include factor H and C4BP in the fluid phase and membrane cofactor protein/CD46 and CR1 on cell surfaces. The presence of these cofactors on healthy cells allows degradation of deposited C3b by CFI in order to prevent undesired complement activation, while in apoptotic cells or microbes, the absence of such cofactors leads to C3b-mediated complement activation and subsequent opsonization.

Belongs to the peptidase S1 family.

67.298 kDa

MKLALLILLLLNPHLSSSKNTPASGQPQEDLVEQKCLLKNYTHHSCDKVFCQPWQKCIEGTCACKLPYQCPKAGTPVCATNGRGYPTYCHLKSFECLHPEIKFSNNGTCTAEEKFNVSLIYGSTDTEGIVQVKLVDQDEKMFICKNSWSTVEANVACFDLGFPLGVRDIQGRFNIPVNHKINSTECLHVRCQGVETSLAECTFTKKSSKAPHGLAGVVCYTQDADFPTSQSFQCVNGKRIPQEKACDGVNDCGDQSDELCCKGCRGQAFLCKSGVCIPNQRKCNGEVDCITGEDESGCEEDKKNKIHKGLARSDQGGETEIETEETEMLTPDMDTERKRIKSLLPKLSCGVKRNTHIRRKRVVGGKPAEMGDYPWQVAIKDGDRITCGGIYIGGCWILTAAHCVRPSRYRNYQVWTSLLDWLKPNSQLAVQGVSRVVVHEKYNGATYQNDIALVEMKKHPGKKECELINSVPACVPWSPYLFQPNDRCIISGWGREKDNQKVYSLRWGEVDLIGNCSRFYPGRYYEKEMQCAGTSDGSIDACKGDSGGPLVCKDVNNVTYVWGIVSWGENCGKPEFPGVYTRVASYFDWISYYVGRPLVSQYNV

Cfi

Complement factor I

603 amino acids

Trypsin-like serine protease that plays an essential role in regulating the immune response by controlling all complement pathways. Inhibits these pathways by cleaving three peptide bonds in the alpha-chain of C3b and two bonds in the alpha-chain of C4b thereby inactivating these proteins. Essential cofactors for these reactions include factor H and C4BP in the fluid phase and membrane cofactor protein/CD46 and CR1 on cell surfaces. The presence of these cofactors on healthy cells allows degradation of deposited C3b by CFI in order to prevent undesired complement activation, while in apoptotic cells or microbes, the absence of such cofactors leads to C3b-mediated complement activation and subsequent opsonization.

Belongs to the peptidase S1 family.

67.261 kDa

MKLAHLSLFLLALHLSSSRSPSASDLPQEELVDQKCLLQKYTHRSCNKVFCQPWQRCIEGTCICKLPYQCPRAGTPVCAMNGRSYPTYCHQKSFECLHPEIKFSHNGTCAAEGKFNVSLIYGRTKTEGLVQVKLVDQDERMFICKNSWSMAEANVACVDLGFPLGVRDIQGSFNISGNLHINDTECLHVHCRGVETSLAECAFTKRRTELSNGLAGVVCYKQDADFPTSLSFQCVNGKHIPQEKACNGVNDCGDQSDELCCKGCRGNASLCKSGVCIPDQYKCNGEVDCITGEDESRCEEDRQQNIPKGLARSAQGEAEIETEETEMLTPGMDNERKRIKSLLPKLSCGVKRNTHTRRKRVIGGKPANVGDYPWQVAIKDGQRITCGGIYIGGCWILTAAHCVRPSRAHSYQVWTALLDWLKPNSQLGIQTVKRVIVHEKYNGATFQNDIALIEMKMHTGKKECELPNSVPACVPWSPYLFQPNDRCIISGWGRGKDNQKVYSLRWGEVDLIGNCSQFYPDRYYEKEMQCAGTRDGSIDACKGDSGGPLVCEDINNVTYVWGIVSWGENCGKPEFPGVYTRVANYFDWISYHVGRSLVSQHNV

CFI

Complement factor I

583 amino acids

Trypsin-like serine protease that plays an essential role in regulating the immune response by controlling all complement pathways. Inhibits these pathways by cleaving three peptide bonds in the alpha-chain of C3b and two bonds in the alpha-chain of C4b thereby inactivating these proteins (PubMed:7360115, PubMed:17320177). Essential cofactors for these reactions include factor H and C4BP in the fluid phase and membrane cofactor protein/CD46 and CR1 on cell surfaces (PubMed:2141838, PubMed:9605165, PubMed:12055245). The presence of these cofactors on healthy cells allows degradation of deposited C3b by CFI in order to prevent undesired complement activation, while in apoptotic cells or microbes, the absence of such cofactors leads to C3b-mediated complement activation and subsequent opsonization (PubMed:28671664).

Belongs to the peptidase S1 family.

65.75 kDa

MKLLHVFLLFLCFHLRFCKVTYTSQEDLVEKKCLAKKYTHLSCDKVFCQPWQRCIEGTCVCKLPYQCPKNGTAVCATNRRSFPTYCQQKSLECLHPGTKFLNNGTCTAEGKFSVSLKHGNTDSEGIVEVKLVDQDKTMFICKSSWSMREANVACLDLGFQQGADTQRRFKLSDLSINSTECLHVHCRGLETSLAECTFTKRRTMGYQDFADVVCYTQKADSPMDDFFQCVNGKYISQMKACDGINDCGDQSDELCCKACQGKGFHCKSGVCIPSQYQCNGEVDCITGEDEVGCAGFASVTQEETEILTADMDAERRRIKSLLPKLSCGVKNRMHIRRKRIVGGKRAQLGDLPWQVAIKDASGITCGGIYIGGCWILTAAHCLRASKTHRYQIWTTVVDWIHPDLKRIVIEYVDRIIFHENYNAGTYQNDIALIEMKKDGNKKDCELPRSIPACVPWSPYLFQPNDTCIVSGWGREKDNERVFSLQWGEVKLISNCSKFYGNRFYEKEMECAGTYDGSIDACKGDSGGPLVCMDANNVTYVWGVVSWGENCGKPEFPGVYTKVANYFDWISYHVGRPFISQYNV

CFI

Complement factor I

583 amino acids

Responsible for cleaving the alpha-chains of C4b and C3b in the presence of the cofactors C4-binding protein and factor H respectively.

Belongs to the peptidase S1 family.

65.62 kDa

MKLLHVFLLFLCFHLSFCKVTYTSQEDLVEKKCLAKKHTHLSCNKVFCQPWQICIEGTCICKLPYQCPKNGTTVCATNGRSFPTYCQQKSLECLRPGTKFLNNGTCTAEGKFSVSLKHGNTDSEGIVEVKLVDQDKTMFICKSSWSMREANVACLDLGFQQGADTQRRFKLSNLSINSTECLHVHCRGLETSLAECTFTKRRTMGYQDLADVVCYTQKADSPTNDFFQCVNGKYISQMKACDGINDCGDQSDELCCKACQGKSFHCKSGVCIPSQYRCNGEVDCITGEDEVGCEGFASVAQEETEILTADMDAERRRIKSLLPKLSCGVKNRRHIRRKRIVGGKRAQLGDLPWQVGIKDASGITCGGIYIGGCWILTAAHCLRASKTHHYQIWTTVVDWIHPDRKRIVIEYVDRIIFHENYNAGTYQNDIALMEMKKDGNKKDCELPRSIPACVPWSPYLFQPNDTCIVSGWGREKDNEKVFSLQWGEVKLISNCSKFYGNRFYEKEMECAGTYDGSIDACKGDSGGPLVCMDANNVTYVWGVVSWGENCGKPEFPGVYTKVANYFDWISYHVGRPFISQYNV