| IED ID | IndEnz0002004773 |
| Enzyme Type ID | protease004773 |
| Protein Name |
Complement factor I EC 3.4.21.45 C3B/C4B inactivator Cleaved into: Complement factor I heavy chain; Complement factor I light chain |
| Gene Name | CFI IF |
| Organism | Homo sapiens (Human) |
| Taxonomic Lineage | cellular organisms Eukaryota Opisthokonta Metazoa Eumetazoa Bilateria Deuterostomia Chordata Craniata Vertebrata Gnathostomata (jawed vertebrates) Teleostomi Euteleostomi Sarcopterygii Dipnotetrapodomorpha Tetrapoda Amniota Mammalia Theria Eutheria Boreoeutheria Euarchontoglires Primates Haplorrhini Simiiformes Catarrhini Hominoidea (apes) Hominidae (great apes) Homininae Homo Homo sapiens (Human) |
| Enzyme Sequence | MKLLHVFLLFLCFHLRFCKVTYTSQEDLVEKKCLAKKYTHLSCDKVFCQPWQRCIEGTCVCKLPYQCPKNGTAVCATNRRSFPTYCQQKSLECLHPGTKFLNNGTCTAEGKFSVSLKHGNTDSEGIVEVKLVDQDKTMFICKSSWSMREANVACLDLGFQQGADTQRRFKLSDLSINSTECLHVHCRGLETSLAECTFTKRRTMGYQDFADVVCYTQKADSPMDDFFQCVNGKYISQMKACDGINDCGDQSDELCCKACQGKGFHCKSGVCIPSQYQCNGEVDCITGEDEVGCAGFASVTQEETEILTADMDAERRRIKSLLPKLSCGVKNRMHIRRKRIVGGKRAQLGDLPWQVAIKDASGITCGGIYIGGCWILTAAHCLRASKTHRYQIWTTVVDWIHPDLKRIVIEYVDRIIFHENYNAGTYQNDIALIEMKKDGNKKDCELPRSIPACVPWSPYLFQPNDTCIVSGWGREKDNERVFSLQWGEVKLISNCSKFYGNRFYEKEMECAGTYDGSIDACKGDSGGPLVCMDANNVTYVWGVVSWGENCGKPEFPGVYTKVANYFDWISYHVGRPFISQYNV |
| Enzyme Length | 583 |
| Uniprot Accession Number | P05156 |
| Absorption | |
| Active Site | ACT_SITE 380; /note=Charge relay system; /evidence=ECO:0000250|UniProtKB:P00750; ACT_SITE 429; /note=Charge relay system; /evidence=ECO:0000250|UniProtKB:P00750; ACT_SITE 525; /note=Charge relay system; /evidence=ECO:0000250|UniProtKB:P00750 |
| Activity Regulation | |
| Binding Site | |
| Calcium Binding | CA_BIND 239..253; /note="1"; /evidence="ECO:0000269|PubMed:21768352, ECO:0007744|PDB:2XRC"; CA_BIND 276..290; /note="2"; /evidence="ECO:0000269|PubMed:21768352, ECO:0007744|PDB:2XRC" |
| catalytic Activity | CATALYTIC ACTIVITY: Reaction=Inactivates complement subcomponents C3b, iC3b and C4b by proteolytic cleavage.; EC=3.4.21.45; |
| DNA Binding | |
| EC Number | 3.4.21.45 |
| Enzyme Function | FUNCTION: 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). {ECO:0000269|PubMed:12055245, ECO:0000269|PubMed:17320177, ECO:0000269|PubMed:2141838, ECO:0000269|PubMed:28671664, ECO:0000269|PubMed:7360115, ECO:0000269|PubMed:9605165}. |
| Temperature Dependency | |
| PH Dependency | |
| Pathway | |
| nucleotide Binding | |
| Features | Active site (3); Beta strand (36); Calcium binding (2); Chain (3); Disulfide bond (21); Domain (5); Erroneous initiation (1); Glycosylation (6); Helix (11); Natural variant (14); Sequence conflict (1); Signal peptide (1); Turn (5) |
| Keywords | 3D-structure;Age-related macular degeneration;Calcium;Cleavage on pair of basic residues;Complement pathway;Direct protein sequencing;Disease variant;Disulfide bond;Glycoprotein;Hemolytic uremic syndrome;Host-virus interaction;Hydrolase;Immunity;Innate immunity;Metal-binding;Protease;Reference proteome;Repeat;Secreted;Serine protease;Signal |
| Interact With | |
| Induction | |
| Subcellular Location | SUBCELLULAR LOCATION: Secreted, extracellular space. Secreted {ECO:0000269|PubMed:6327681}. |
| Modified Residue | |
| Post Translational Modification | |
| Signal Peptide | SIGNAL 1..18 |
| Structure 3D | X-ray crystallography (2) |
| Cross Reference PDB | 2XRC; 5O32; |
| Mapped Pubmed ID | 1386357; 14967308; 15210795; 15835912; 16237761; 16386793; 16920989; 17055788; 17067565; 17482181; 17548110; 17597211; 17599974; 18374984; 18566438; 18658028; 18685559; 18701018; 18805611; 18825487; 19065647; 19661236; 19693526; 19861685; 20016463; 20044478; 20059470; 20087399; 20106822; 20332099; 20379614; 20385819; 20888482; 21316765; 21788512; 21936007; 22223611; 22258234; 22393059; 22514678; 22594569; 22678500; 22710145; 22926405; 23519521; 23688582; 23722394; 23731345; 24142231; 24642830; 24732209; 24983375; 25075123; 25184960; 25188723; 25352734; 25394898; 25618258; 25788521; 25803806; 25986072; 26312598; 26613809; 26767664; 26900322; 27268256; 27380463; 28282489; 28455885; 28942469; 29292855; 293746; 29696024; 2971659; 29888403; 301546; 30253188; 30987833; 31614353; 32215612; 32510551; 3848661; 6214588; 6219696; 6607952; 702059; 7391570; |
| Motif | |
| Gene Encoded By | |
| Mass | 65,750 |
| Kinetics | |
| Metal Binding | |
| Rhea ID | |
| Cross Reference Brenda | 3.4.21.45; |