ID   C1S_BOVIN               Reviewed;         689 AA.
AC   Q0VCX1;
DT   01-MAY-2007, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-2007, sequence version 2.
DT   02-SEP-2026, entry version 113.
DE   RecName: Full=Complement C1s subcomponent;
DE            EC=3.4.21.42 {ECO:0000250|UniProtKB:P09871};
DE   AltName: Full=C1 esterase;
DE   AltName: Full=Complement component 1 subcomponent s;
DE   Contains:
DE     RecName: Full=Complement C1s subcomponent heavy chain;
DE   Contains:
DE     RecName: Full=Complement C1s subcomponent light chain;
DE   Flags: Precursor;
GN   Name=C1S;
OS   Bos taurus (Bovine).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Artiodactyla; Ruminantia; Pecora; Bovidae;
OC   Bovinae; Bos.
OX   NCBI_TaxID=9913;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
RC   STRAIN=Hereford; TISSUE=Fetal skin;
RG   NIH - Mammalian Gene Collection (MGC) project;
RL   Submitted (AUG-2006) to the EMBL/GenBank/DDBJ databases.
CC   -!- FUNCTION: Component of the complement C1 complex, a multiprotein
CC       complex that initiates the classical pathway of the complement system,
CC       a cascade of proteins that leads to phagocytosis and breakdown of
CC       pathogens and signaling that strengthens the adaptive immune system.
CC       C1S is activated following association of the C1 complex with
CC       immunoglobulins (IgG or IgM) complexed with antigens to form antigen-
CC       antibody complexes on the surface of pathogens. C1S is cleaved and
CC       activated by C1R to generate C1s subcomponent heavy and light chains.
CC       C1s subcomponent light chain then cleaves and activates C2 and C4, the
CC       next components of the classical complement pathway.
CC       {ECO:0000250|UniProtKB:P09871}.
CC   -!- FUNCTION: [Complement C1s subcomponent light chain]: Serine protease
CC       component of the complement C1 complex, which catalyzes cleavage and
CC       activation of C2 and C4, the next components of the classical
CC       complement pathway. Also cleaves IGFBP5 and thereby inhibits the
CC       trophic effects of IGF1. {ECO:0000250|UniProtKB:P09871}.
CC   -!- CATALYTIC ACTIVITY: [Complement C1s subcomponent light chain]:
CC       Reaction=Cleavage of Arg-|-Ala bond in complement component C4 to form
CC         C4a and C4b, and Lys(or Arg)-|-Lys bond in complement component C2 to
CC         form C2a and C2b: the 'classical' pathway C3 convertase.;
CC         EC=3.4.21.42; Evidence={ECO:0000250|UniProtKB:P09871};
CC   -!- ACTIVITY REGULATION: Cleaved and activated by C1R. Immunoglobulin-
CC       binding promotes autoactivation of C1R, which results in the cleavage
CC       of the Arg-Ile bond in the catalytic domain. Inhibited by C1 inhibitor
CC       (SERPING1). {ECO:0000250|UniProtKB:P09871}.
CC   -!- SUBUNIT: Core component of the complement C1 complex, a calcium-
CC       dependent complex composed of 1 molecule of the C1Q subcomplex, 2
CC       molecules of C1R and 2 molecules of C1S. The C1Q subcomplex is composed
CC       18 subunits: 3 chains of C1QA, C1QB, and C1QC trimerize to form 6
CC       collagen-like triple helices connected to six globular ligand-
CC       recognition modules. {ECO:0000250|UniProtKB:P09871}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250|UniProtKB:P09871}. Cell
CC       surface {ECO:0000250|UniProtKB:P09871}. Note=Recruited to the surface
CC       of pathogens by the C1Q subcomplex. {ECO:0000250|UniProtKB:P09871}.
CC   -!- PTM: Cleaved and activated by C1R to generate Complement C1s
CC       subcomponent heavy and light chains. {ECO:0000250|UniProtKB:P09871}.
CC   -!- PTM: The iron and 2-oxoglutarate dependent 3-hydroxylation of aspartate
CC       and asparagine is (R) stereospecific within EGF domains.
CC       {ECO:0000250|UniProtKB:P09871}.
CC   -!- SIMILARITY: Belongs to the peptidase S1 family. {ECO:0000255|PROSITE-
CC       ProRule:PRU00274}.
CC   -!- SEQUENCE CAUTION:
CC       Sequence=AAI19957.1; Type=Erroneous initiation; Evidence={ECO:0000305};
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DR   EMBL; BC119956; AAI19957.1; ALT_INIT; mRNA.
DR   RefSeq; NP_001070018.1; NM_001076550.1.
DR   AlphaFoldDB; Q0VCX1; -.
DR   SMR; Q0VCX1; -.
DR   BioGRID; 612993; 1.
DR   FunCoup; Q0VCX1; 294.
DR   STRING; 9913.ENSBTAP00000066104; -.
DR   MEROPS; S01.193; -.
DR   GlyCosmos; Q0VCX1; 3 sites, No reported glycans.
DR   GlyGen; Q0VCX1; 3 sites.
DR   PaxDb; 9913-ENSBTAP00000066104; -.
DR   PeptideAtlas; Q0VCX1; -.
DR   GeneID; 767827; -.
DR   KEGG; bta:767827; -.
DR   CTD; 716; -.
DR   eggNOG; KOG3627; Eukaryota.
DR   InParanoid; Q0VCX1; -.
DR   OrthoDB; 9985152at2759; -.
DR   Proteomes; UP000009136; Unplaced.
DR   GO; GO:0009986; C:cell surface; ISS:UniProtKB.
DR   GO; GO:0005576; C:extracellular region; ISS:UniProtKB.
DR   GO; GO:0106139; C:symbiont cell surface; ISS:UniProtKB.
DR   GO; GO:0005509; F:calcium ion binding; IEA:InterPro.
DR   GO; GO:0004252; F:serine-type endopeptidase activity; ISS:UniProtKB.
DR   GO; GO:0006956; P:complement activation; IEA:InterPro.
DR   GO; GO:0006508; P:proteolysis; IEA:InterPro.
DR   CDD; cd00033; CCP; 2.
DR   CDD; cd00041; CUB; 2.
DR   CDD; cd00054; EGF_CA; 1.
DR   CDD; cd00190; Tryp_SPc; 1.
DR   FunFam; 2.10.70.10:FF:000049; Complement C1s subcomponent; 1.
DR   FunFam; 2.40.10.10:FF:000067; Complement C1s subcomponent; 1.
DR   FunFam; 2.60.120.290:FF:000034; complement C1s subcomponent; 1.
DR   FunFam; 2.10.25.10:FF:000059; Mannan-binding lectin serine protease 1; 1.
DR   FunFam; 2.10.70.10:FF:000016; Mannan-binding lectin serine protease 1; 1.
DR   FunFam; 2.60.120.290:FF:000006; Mannan-binding lectin serine protease 1; 1.
DR   Gene3D; 2.10.70.10; Complement Module, domain 1; 2.
DR   Gene3D; 2.10.25.10; Laminin; 1.
DR   Gene3D; 2.60.120.290; Spermadhesin, CUB domain; 2.
DR   Gene3D; 2.40.10.10; Trypsin-like serine proteases; 2.
DR   InterPro; IPR000859; CUB_dom.
DR   InterPro; IPR001881; EGF-like_Ca-bd_dom.
DR   InterPro; IPR000152; EGF-type_Asp/Asn_hydroxyl_site.
DR   InterPro; IPR018097; EGF_Ca-bd_CS.
DR   InterPro; IPR024175; Pept_S1A_C1r/C1S/mannan-bd.
DR   InterPro; IPR009003; Peptidase_S1_PA.
DR   InterPro; IPR001314; Peptidase_S1A.
DR   InterPro; IPR035914; Sperma_CUB_dom_sf.
DR   InterPro; IPR035976; Sushi/SCR/CCP_sf.
DR   InterPro; IPR000436; Sushi_SCR_CCP_dom.
DR   InterPro; IPR001254; Trypsin_dom.
DR   InterPro; IPR033116; TRYPSIN_SER.
DR   PANTHER; PTHR24255:SF18; COMPLEMENT C1S SUBCOMPONENT; 1.
DR   PANTHER; PTHR24255; COMPLEMENT COMPONENT 1, S SUBCOMPONENT-RELATED; 1.
DR   Pfam; PF00431; CUB; 2.
DR   Pfam; PF14670; FXa_inhibition; 1.
DR   Pfam; PF00084; Sushi; 2.
DR   Pfam; PF00089; Trypsin; 1.
DR   PIRSF; PIRSF001155; C1r_C1s_MASP; 1.
DR   PRINTS; PR00722; CHYMOTRYPSIN.
DR   SMART; SM00032; CCP; 2.
DR   SMART; SM00042; CUB; 2.
DR   SMART; SM00179; EGF_CA; 1.
DR   SMART; SM00020; Tryp_SPc; 1.
DR   SUPFAM; SSF57535; Complement control module/SCR domain; 2.
DR   SUPFAM; SSF57196; EGF/Laminin; 1.
DR   SUPFAM; SSF49854; Spermadhesin, CUB domain; 2.
DR   SUPFAM; SSF50494; Trypsin-like serine proteases; 1.
DR   PROSITE; PS00010; ASX_HYDROXYL; 1.
DR   PROSITE; PS01180; CUB; 2.
DR   PROSITE; PS01187; EGF_CA; 1.
DR   PROSITE; PS50923; SUSHI; 2.
DR   PROSITE; PS50240; TRYPSIN_DOM; 1.
DR   PROSITE; PS00135; TRYPSIN_SER; 1.
PE   2: Evidence at transcript level;
KW   Calcium; Complement pathway; Disulfide bond; EGF-like domain; Glycoprotein;
KW   Hydrolase; Hydroxylation; Immunity; Innate immunity; Metal-binding;
KW   Protease; Reference proteome; Repeat; Secreted; Serine protease; Signal;
KW   Sushi.
FT   SIGNAL          1..15
FT                   /evidence="ECO:0000255"
FT   CHAIN           16..689
FT                   /note="Complement C1s subcomponent"
FT                   /id="PRO_0000285867"
FT   CHAIN           16..437
FT                   /note="Complement C1s subcomponent heavy chain"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT                   /id="PRO_0000285868"
FT   CHAIN           438..689
FT                   /note="Complement C1s subcomponent light chain"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT                   /id="PRO_0000285869"
FT   DOMAIN          16..130
FT                   /note="CUB 1"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00059"
FT   DOMAIN          131..172
FT                   /note="EGF-like; calcium-binding"
FT                   /evidence="ECO:0000255"
FT   DOMAIN          175..290
FT                   /note="CUB 2"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00059"
FT   DOMAIN          292..356
FT                   /note="Sushi 1"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00302"
FT   DOMAIN          357..423
FT                   /note="Sushi 2"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00302"
FT   DOMAIN          438..681
FT                   /note="Peptidase S1"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   ACT_SITE        475
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   ACT_SITE        529
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   ACT_SITE        632
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         60
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         68
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         113
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         131
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         132
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         134
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         149
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         150
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         153
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         226
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="3"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         236
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="3"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         275
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="3"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   BINDING         279
FT                   /ligand="Ca(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29108"
FT                   /ligand_label="3"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   SITE            437..438
FT                   /note="Cleavage; by C1R"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   MOD_RES         149
FT                   /note="(3R)-3-hydroxyasparagine"
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   CARBOHYD        64
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   CARBOHYD        174
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   CARBOHYD        406
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   DISULFID        65..83
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        135..147
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        143..156
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        158..171
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        175..202
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        234..251
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        294..341
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        321..354
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        359..403
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        386..421
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        425..549
FT                   /note="Interchain (between heavy and light chains)"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00059,
FT                   ECO:0000255|PROSITE-ProRule:PRU00274, ECO:0000255|PROSITE-
FT                   ProRule:PRU00302"
FT   DISULFID        595..618
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
FT   DISULFID        628..660
FT                   /evidence="ECO:0000250|UniProtKB:P09871"
SQ   SEQUENCE   689 AA;  76609 MW;  B10A00EC4B15465C CRC64;
     MWCIVLFSLV AWVYAEPTMY GEILSPNYPQ VYPNEVEKSW DIEVPAGYGI HLYFTHLDIE
     LSENCSYDSV QIMSGGHEEG KLCGRRTNKN SNSPVVKEFH IPYSKLQVIF RSDFSNEERF
     TGFAAYYVAE DIDECTAFAD APCSHFCNNF LGGYFCSCPP EYFLHEDKKN CGVNCSGNVF
     TTMTGEVESP NYPSPYPESS RCDYQIQLEE GFRVVVTMRR EDFDVEPADS EGHCPDSLLF
     VAGDQHFGPY CGNGFPGPLT IETQSSALNI IFQTDGSEQR KGWKFRYHGD PIPCPKEVTA
     NSFWEPERAK YVFRDVVKIT CVDGFEVVQG SVGSPSFYST CQSNGKWSNS KLRCQPVDCG
     APEPIQHGRV EDPESTLFGS ITRYSCEMPY YSMECEGSEV YHCSGNGSWV NKVLGIEPPK
     CIAVCGTPSE PFRSTQRIFG GSIAKIENFP WQVFFSNPWA GGALIDEYWV LTAAHVVEGN
     DIPVMYVGSS SVVTSQLSNA QMLTAERVFI HPGWEVLDPS ITRKNFDNDI ALVRLRDPVK
     MGPKVAPICL PGTSSEYDPP ENVLGLISGW GRTNVKSHVI KLRGAKLPVA PLSKCREMKG
     VNPGIDISSF VFTENMICAG NDKGVDSCDG DSGGAFAVQD PKENKPKFYV AGLVSWGPQC
     GTYGIYTRVK NYVDWIRKTM QEYSAPSVD
//