complement component 1r complement component 1r complement c1r subcomponent (ec 3.4.21.41, activated complement c1r, c overbar 1r esterase, c1r) is a protein involved in the complement system of the innate immune system. in humans, c1r is encoded by the c1r gene. c1ravailable structurespdbortholog search: pdbe rcsb list of pdb id codes1apq, 1gpz, 1md7, 1md8, 2qy0identifiersaliasesc1r, complement c1r, edspd1external idsomim: 613785 mgi: 3779804 homologene: 1313 genecards: c1r gene location (human)chr.chromosome 12 (human)band12p13.31start7,080,214 bpend7,092,540 bpgene location (mouse)chr.chromosome 6 (mouse)band6 f2|6start124,547,253 bpend124,558,130 bprna expression patternbgeehumanmouse (ortholog)top expressed inright lobe of livergallbladderright coronary arterygastric mucosaleft uterine tubeleft coronary arteryurinary bladdercanal of the cervixtibial nervemyometriumtop expressed inwhite adipose tissueadrenal glandurinary bladderliverovaryskeletal muscle tissuespleenislet of langerhanslungtesticlemore reference expression databiogpsn/agene ontologymolecular function peptidase activity serine-type peptidase activity serine-type endopeptidase activity protein binding hydrolase activity calcium ion binding cellular component extracellular region blood microparticle extracellular exosome extracellular space biological process immune response proteolysis complement activation, classical pathway immune system process innate immune response complement activation regulation of complement activation zymogen activation sources:amigo / quickgoorthologsspecieshumanmouseentrez715667277ensemblensg00000159403ensg00000288512ensmusg00000098470uniprotp00736q8cfg9refseq (mrna)nm_001733nm_001354346nm_001113356refseq (protein)np_001724np_001341275np_001106827location (ucsc)chr 12: 7.08 – 7.09 mbchr 6: 124.55 – 124.56 mbpubmed searchwikidataview/edit humanview/edit mouse c1r along with c1q and c1s form the c1 complex, which is the first component of the serum complement system. c1r is an enzyme that activates c1s to its active form, by proteolytic cleavage. clinical significance ehlers-danlos syndrome periodontal type is associated with mutations in the cr1 gene function c1r has been shown to interact with c1s. c1r cleaves c1s to form the active form of c1s.