ID   CO3_NAJNA               Reviewed;        1651 AA.
AC   Q01833;
DT   01-JUL-1993, integrated into UniProtKB/Swiss-Prot.
DT   01-JUL-1993, sequence version 1.
DT   03-AUG-2022, entry version 105.
DE   RecName: Full=Complement C3;
DE   Contains:
DE     RecName: Full=Complement C3 beta chain;
DE   Contains:
DE     RecName: Full=Complement C3 alpha chain;
DE   Contains:
DE     RecName: Full=C3a anaphylatoxin;
DE   Contains:
DE     RecName: Full=Complement C3b alpha' chain;
DE   Contains:
DE     RecName: Full=Complement C3f fragment;
DE   Flags: Precursor;
GN   Name=C3;
OS   Naja naja (Indian cobra).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Elapinae; Naja.
OX   NCBI_TaxID=35670;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Liver;
RX   PubMed=1431125;
RA   Fritzinger D.C., Connelly M., Petrella E.C., Bredehorst R., Vogel C.-W.;
RT   "Primary structure of cobra complement component C3.";
RL   J. Immunol. 149:3554-3562(1992).
CC   -!- FUNCTION: C3 plays a central role in the activation of the complement
CC       system. Its processing by C3 convertase is the central reaction in both
CC       classical and alternative complement pathways. After activation C3b can
CC       bind covalently, via its reactive thioester, to cell surface
CC       carbohydrates or immune aggregates.
CC   -!- FUNCTION: Derived from proteolytic degradation of complement C3, C3a
CC       anaphylatoxin is a mediator of local inflammatory process. It induces
CC       the contraction of smooth muscle, increases vascular permeability and
CC       causes histamine release from mast cells and basophilic leukocytes.
CC   -!- SUBUNIT: C3 precursor is first processed by the removal of 4 Arg
CC       residues, forming two chains, beta and alpha, linked by a disulfide
CC       bond. C3 convertase activates C3 by cleaving the alpha chain, releasing
CC       C3a anaphylatoxin and generating C3b (beta chain + alpha' chain) (By
CC       similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Secreted.
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DR   EMBL; L02365; AAA49385.1; -; mRNA.
DR   AlphaFoldDB; Q01833; -.
DR   SMR; Q01833; -.
DR   MEROPS; I39.950; -.
DR   PRIDE; Q01833; -.
DR   Proteomes; UP000694559; Unplaced.
DR   GO; GO:0005615; C:extracellular space; IEA:InterPro.
DR   GO; GO:0004866; F:endopeptidase inhibitor activity; IEA:InterPro.
DR   GO; GO:0006957; P:complement activation, alternative pathway; IEA:UniProtKB-KW.
DR   GO; GO:0006958; P:complement activation, classical pathway; IEA:UniProtKB-KW.
DR   GO; GO:0006954; P:inflammatory response; IEA:UniProtKB-KW.
DR   CDD; cd00017; ANATO; 1.
DR   CDD; cd03583; NTR_complement_C3; 1.
DR   Gene3D; 2.40.50.120; -; 1.
DR   Gene3D; 2.60.40.10; -; 2.
DR   Gene3D; 2.60.40.690; -; 1.
DR   InterPro; IPR009048; A-macroglobulin_rcpt-bd.
DR   InterPro; IPR036595; A-macroglobulin_rcpt-bd_sf.
DR   InterPro; IPR011625; A2M_N_BRD.
DR   InterPro; IPR011626; Alpha-macroglobulin_TED.
DR   InterPro; IPR000020; Anaphylatoxin/fibulin.
DR   InterPro; IPR018081; Anaphylatoxin_comp_syst.
DR   InterPro; IPR001840; Anaphylatoxn_comp_syst_dom.
DR   InterPro; IPR041425; C3/4/5_MG1.
DR   InterPro; IPR035711; Complement_C3-like.
DR   InterPro; IPR013783; Ig-like_fold.
DR   InterPro; IPR001599; Macroglobln_a2.
DR   InterPro; IPR019742; MacrogloblnA2_CS.
DR   InterPro; IPR002890; MG2.
DR   InterPro; IPR041555; MG3.
DR   InterPro; IPR040839; MG4.
DR   InterPro; IPR001134; Netrin_domain.
DR   InterPro; IPR018933; Netrin_module_non-TIMP.
DR   InterPro; IPR035815; NTR_complement_C3.
DR   InterPro; IPR008930; Terpenoid_cyclase/PrenylTrfase.
DR   InterPro; IPR008993; TIMP-like_OB-fold.
DR   PANTHER; PTHR11412:SF81; PTHR11412:SF81; 1.
DR   Pfam; PF00207; A2M; 1.
DR   Pfam; PF07703; A2M_BRD; 1.
DR   Pfam; PF07677; A2M_recep; 1.
DR   Pfam; PF01821; ANATO; 1.
DR   Pfam; PF17790; MG1; 1.
DR   Pfam; PF01835; MG2; 1.
DR   Pfam; PF17791; MG3; 1.
DR   Pfam; PF17789; MG4; 1.
DR   Pfam; PF01759; NTR; 1.
DR   Pfam; PF07678; TED_complement; 1.
DR   PRINTS; PR00004; ANAPHYLATOXN.
DR   SMART; SM01360; A2M; 1.
DR   SMART; SM01359; A2M_N_2; 1.
DR   SMART; SM01361; A2M_recep; 1.
DR   SMART; SM00104; ANATO; 1.
DR   SMART; SM00643; C345C; 1.
DR   SUPFAM; SSF47686; SSF47686; 1.
DR   SUPFAM; SSF48239; SSF48239; 1.
DR   SUPFAM; SSF49410; SSF49410; 1.
DR   SUPFAM; SSF50242; SSF50242; 1.
DR   PROSITE; PS00477; ALPHA_2_MACROGLOBULIN; 1.
DR   PROSITE; PS01177; ANAPHYLATOXIN_1; 1.
DR   PROSITE; PS01178; ANAPHYLATOXIN_2; 1.
DR   PROSITE; PS50189; NTR; 1.
PE   2: Evidence at transcript level;
KW   Complement alternate pathway; Complement pathway; Disulfide bond; Immunity;
KW   Inflammatory response; Innate immunity; Reference proteome; Secreted;
KW   Signal; Thioester bond.
FT   SIGNAL          1..22
FT                   /evidence="ECO:0000250"
FT   CHAIN           23..1651
FT                   /note="Complement C3"
FT                   /id="PRO_0000288818"
FT   CHAIN           23..655
FT                   /note="Complement C3 beta chain"
FT                   /id="PRO_0000288819"
FT   CHAIN           661..1651
FT                   /note="Complement C3 alpha chain"
FT                   /id="PRO_0000288820"
FT   PEPTIDE         661..738
FT                   /note="C3a anaphylatoxin"
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000288821"
FT   CHAIN           739..1651
FT                   /note="Complement C3b alpha' chain"
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000288822"
FT   PEPTIDE         1291..1307
FT                   /note="Complement C3f fragment"
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000288823"
FT   DOMAIN          683..718
FT                   /note="Anaphylatoxin-like"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00022"
FT   DOMAIN          1506..1649
FT                   /note="NTR"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00295"
FT   REGION          660..738
FT                   /note="C3a-like domain"
FT   REGION          991..1269
FT                   /note="C3d-like domain"
FT   REGION          1412..1444
FT                   /note="Properdin-binding"
FT                   /evidence="ECO:0000250"
FT   SITE            738..739
FT                   /note="Cleavage; by C3 convertase"
FT   SITE            1290..1291
FT                   /note="Cleavage; by factor I"
FT                   /evidence="ECO:0000250"
FT   SITE            1307..1308
FT                   /note="Cleavage; by factor I"
FT                   /evidence="ECO:0000250"
FT   DISULFID        546..807
FT                   /note="Interchain (between beta and alpha chains)"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00022,
FT                   ECO:0000255|PROSITE-ProRule:PRU00295"
FT   DISULFID        615..650
FT                   /evidence="ECO:0000250"
FT   DISULFID        683..710
FT                   /evidence="ECO:0000250"
FT   DISULFID        684..717
FT                   /evidence="ECO:0000250"
FT   DISULFID        697..718
FT                   /evidence="ECO:0000250"
FT   DISULFID        863..1501
FT                   /evidence="ECO:0000250"
FT   DISULFID        1091..1147
FT                   /evidence="ECO:0000250"
FT   DISULFID        1346..1477
FT                   /evidence="ECO:0000250"
FT   DISULFID        1377..1446
FT                   /evidence="ECO:0000250"
FT   DISULFID        1494..1499
FT                   /evidence="ECO:0000250"
FT   DISULFID        1506..1578
FT                   /evidence="ECO:0000250"
FT   DISULFID        1525..1649
FT                   /evidence="ECO:0000250"
FT   DISULFID        1625..1634
FT                   /evidence="ECO:0000250"
FT   CROSSLNK        999..1002
FT                   /note="Isoglutamyl cysteine thioester (Cys-Gln)"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   1651 AA;  184927 MW;  66F91BD8F4A935F7 CRC64;
     MEGMALYLVA ALLIGFPGSS HGALYTLITP AVLRTDTEEQ ILVEAHGDST PKSLDIFVHD
     FPRKQKTLFQ SRVDMNQAGS MFVTPTIKVP AKELNKDSKQ NQYVVVKVTG PQVALEKVVL
     LSYQSGFVFI QTDKGIYTPG SPVRYRVFSV DHNMHRMDKT VIVEFQTPEG IVVSSKPVNP
     SGSIRPYNLP ELVSFGTWKA VAKYEHSPEE SYTAYFDVRE YVLPSFEVRL QPSDKFLYID
     GNKNFHVSIT ARYLYGKKVE GVAFVVFGVK IDDAKKSIPD SLTRIPIIDG DGEATLKRDT
     LRSRFQDLNQ LVGHTLYVSV TVITESGSDM VVTEQGGIHI VTSPYQIYFT KTPKYFKPGM
     PYELTVYVTN PDGSPAAHVP VVSEAIHSEG TTLSDGTAKL ILNTPLNIQS LPITVRTNHG
     DLPRERQAIK SMTATAYQTQ GGSENYLHVA ITSTEIKPGD NLPVNFNVRG NANSLNQIKY
     FTYLILNKGK IFKVGRQPRR DGQNLVTMNL HITPDLIPSF RFVAYYQVGN NEIVADSVWV
     DVKDTCMGTL VVKGASSRDD RIQKPGAAMK IKLEGDPGAR VGLVAVDKAV YVLNDKYKIS
     QAKIWDTIEK SDFGCTAGSG QNNLGVFEDA GLALTTSTNL NTKQRSAAKC PQPANRRRRS
     SVLLLDSKAS KAAQFQDQGL RKCCEDGMHE NPMGYTCEKR AKYIQEGDAC KAAFLECCHY
     IKGIRDENQR ESELFLARSD FEDELFGDDN IISRSDFPES WLWLTEELTG EPNNQGISSK
     TVPFYLRDSI TTWELLAVGL SPTKGICVAE PYEITVMKDF FIDLRLPYSV VKNEQVEIRA
     ILYNYADEDI YVRVELIYNP AFCSASTEGQ RYRQQFPIKA LSSRAVPFVI VPLEQGLHDV
     EVIASVRGEL ASDGVRKKLK VVPEGERKNI VTIIELDPSV KGVGGTQELT VIANKLDDKV
     PDTEVETRIS VLGDPVAQII ENSIDGSKLN HLIITPSGCG EQNMITMTPS VIATYYLDAT
     GQWENLGVDR RTEAIKQIMT GYAQQMVYKK ADHSYAAFTN RASSSWLTAY VVKVLAMASN
     MVKDISHEII CGGVKWLILN RQQPDGVFKE NAPVIHGEML GGTKGAEPEA SLTAFIVTAL
     LESRSVCKEQ INILDSSINK ATDYLLKKYE KLQRPYTTAL TAYALAAADR LNDDRVLMAA
     STGRNRWEEY NARTHNIEGT SYALLALLKM KKFAEVGPVV RWLIDQKYYG GTYGQTQATV
     MVFQALAEYE IQMPTHQDLN LDISIKLPER EVPERYSIND RNAVQARTVE TKLNEDFTVS
     ASGDGKATMT ILTVYNAQLR EDANVCNKFH LDVSVENVEL NLKQAKGGKA ALRLKICTRY
     LGEVDSTMTI IDISMLTGFF PDAEDLKRLS NGVDRYISKF EIDNNMAQKG TVVIYLDKVS
     HSEDECLHFK IHKHFEVGFI QPGSVKVYSY YNLDEQCTKF YHPDKETGLL NKICHGNICR
     CAEETCSLLN QQKKIDLQLR IQKACAQNVD YVYKTKLLRI EEKDGNDIYF MDVLEVIKGG
     TDRNAQAKAR QYVSQRKCQE ALNLKLDNDY LIWGLSSDLW PMKDDISYLI TKNTWIERWP
     NEDECQDEEF QNLCDDFAQL SNTLTIFGCP T