ID   CFGB_TACTR              Reviewed;         309 AA.
AC   Q27083;
DT   17-JUN-2020, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   25-MAY-2022, entry version 89.
DE   RecName: Full=Clotting factor G beta subunit {ECO:0000303|PubMed:8288603};
DE            EC=3.4.21.85 {ECO:0000269|PubMed:7822328, ECO:0000269|PubMed:8798603};
DE   Contains:
DE     RecName: Full=Clotting factor G beta subunit light chain {ECO:0000305};
DE   Contains:
DE     RecName: Full=Clotting factor G beta subunit heavy chain {ECO:0000305};
DE   Flags: Precursor;
OS   Tachypleus tridentatus (Japanese horseshoe crab).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Merostomata;
OC   Xiphosura; Limulidae; Tachypleus.
OX   NCBI_TaxID=6853 {ECO:0000312|EMBL:BAA04045.1};
RN   [1] {ECO:0000312|EMBL:BAA04045.1}
RP   NUCLEOTIDE SEQUENCE [MRNA], PROTEIN SEQUENCE OF 32-69; 82-118; 174-184 AND
RP   190-257, SUBUNIT, TISSUE SPECIFICITY, AND DISULFIDE BOND.
RX   PubMed=8288603; DOI=10.1016/s0021-9258(17)42267-8;
RA   Seki N., Muta T., Oda T., Iwaki D., Kuma K., Miyata T., Iwanaga S.;
RT   "Horseshoe crab (1,3)-beta-D-glucan-sensitive coagulation factor G. A
RT   serine protease zymogen heterodimer with similarities to beta-glucan-
RT   binding proteins.";
RL   J. Biol. Chem. 269:1370-1374(1994).
RN   [2] {ECO:0000305}
RP   FUNCTION, CATALYTIC ACTIVITY, ACTIVITY REGULATION, SUBUNIT, TISSUE
RP   SPECIFICITY, BIOTECHNOLOGY, AND DISULFIDE BOND.
RX   PubMed=7822328; DOI=10.1074/jbc.270.2.892;
RA   Muta T., Seki N., Takaki Y., Hashimoto R., Oda T., Iwanaga A., Tokunaga F.,
RA   Iwanaga S.;
RT   "Purified horseshoe crab factor G. Reconstitution and characterization of
RT   the (1-->3)-beta-D-glucan-sensitive serine protease cascade.";
RL   J. Biol. Chem. 270:892-897(1995).
RN   [3] {ECO:0000305}
RP   CATALYTIC ACTIVITY, ACTIVITY REGULATION, AND SUBUNIT.
RX   PubMed=8798603; DOI=10.1074/jbc.271.39.23768;
RA   Agarwala K.L., Kawabata S., Miura Y., Kuroki Y., Iwanaga S.;
RT   "Limulus intracellular coagulation inhibitor type 3. Purification,
RT   characterization, cDNA cloning, and tissue localization.";
RL   J. Biol. Chem. 271:23768-23774(1996).
CC   -!- FUNCTION: Component of the heterodimer clotting factor G which may play
CC       a role in defense mechanisms against fungi (Probable). Initiates a
CC       (1->3)-beta-glucan-sensing clotting pathway whereby the alpha subunit
CC       binds to glucans containing (1->3)-beta linkages, which are components
CC       of the fungal cell wall, and the beta subunit catalyzes the activation
CC       of proclotting enzyme (PubMed:7822328). {ECO:0000269|PubMed:7822328,
CC       ECO:0000305|PubMed:7822328}.
CC   -!- CATALYTIC ACTIVITY:
CC       Reaction=Selective cleavage of 98-Arg-|-Ile-99 bond in Limulus
CC         proclotting enzyme to form active clotting enzyme.; EC=3.4.21.85;
CC         Evidence={ECO:0000269|PubMed:7822328, ECO:0000269|PubMed:8798603};
CC   -!- ACTIVITY REGULATION: Binding to (1->3)-beta-D-glucan to alpha subunit,
CC       induces autocatalysis and activation of beta subunit (PubMed:7822328).
CC       Inhibited by intracellular coagulation inhibitor 3/LICI-3 and to a
CC       lesser extend by intracellular coagulation inhibitor 2/LICI-2
CC       (PubMed:7822328, PubMed:8798603). {ECO:0000269|PubMed:7822328,
CC       ECO:0000269|PubMed:8798603}.
CC   -!- SUBUNIT: Clotting factor G is a heterodimer composed of two non-
CC       covalently associated subunits, alpha and beta (PubMed:7822328). Upon
CC       activation, converted to a two-chain active form linked by a disulfide
CC       bond (PubMed:7822328). Forms a covalent heterodimer with intracellular
CC       coagulation inhibitor 3/LICI-3 (PubMed:8798603).
CC       {ECO:0000269|PubMed:7822328, ECO:0000269|PubMed:8798603}.
CC   -!- TISSUE SPECIFICITY: Expressed in the hemocytes (at protein level).
CC       {ECO:0000269|PubMed:7822328, ECO:0000269|PubMed:8288603}.
CC   -!- BIOTECHNOLOGY: Clotting factor G is a component of the Limulus test
CC       used to detect bacterial endotoxins in fluids.
CC       {ECO:0000305|PubMed:7822328}.
CC   -!- SIMILARITY: Belongs to the peptidase S1 family. {ECO:0000305}.
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DR   EMBL; D16623; BAA04045.1; -; mRNA.
DR   PIR; B49878; B49878.
DR   AlphaFoldDB; Q27083; -.
DR   SMR; Q27083; -.
DR   MEROPS; S01.222; -.
DR   GO; GO:0004252; F:serine-type endopeptidase activity; IDA:UniProtKB.
DR   GO; GO:0008236; F:serine-type peptidase activity; IDA:UniProtKB.
DR   GO; GO:0042381; P:hemolymph coagulation; IDA:UniProtKB.
DR   GO; GO:0016485; P:protein processing; IDA:UniProtKB.
DR   CDD; cd00190; Tryp_SPc; 1.
DR   Gene3D; 2.40.10.10; -; 1.
DR   InterPro; IPR009003; Peptidase_S1_PA.
DR   InterPro; IPR043504; Peptidase_S1_PA_chymotrypsin.
DR   InterPro; IPR001314; Peptidase_S1A.
DR   InterPro; IPR001254; Trypsin_dom.
DR   InterPro; IPR018114; TRYPSIN_HIS.
DR   InterPro; IPR033116; TRYPSIN_SER.
DR   Pfam; PF00089; Trypsin; 1.
DR   PRINTS; PR00722; CHYMOTRYPSIN.
DR   SMART; SM00020; Tryp_SPc; 1.
DR   SUPFAM; SSF50494; SSF50494; 1.
DR   PROSITE; PS50240; TRYPSIN_DOM; 1.
DR   PROSITE; PS00134; TRYPSIN_HIS; 1.
DR   PROSITE; PS00135; TRYPSIN_SER; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Glycoprotein;
KW   Hemolymph clotting; Hydrolase; Protease; Serine protease; Signal; Zymogen.
FT   SIGNAL          1..31
FT                   /evidence="ECO:0000269|PubMed:8288603"
FT   CHAIN           32..46
FT                   /note="Clotting factor G beta subunit light chain"
FT                   /evidence="ECO:0000269|PubMed:8288603"
FT                   /id="PRO_0000450356"
FT   CHAIN           47..309
FT                   /note="Clotting factor G beta subunit heavy chain"
FT                   /evidence="ECO:0000269|PubMed:8288603"
FT                   /id="PRO_5004203470"
FT   DOMAIN          47..292
FT                   /note="Peptidase S1"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   ACT_SITE        89
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   ACT_SITE        138
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   ACT_SITE        242
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   CARBOHYD        100
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00498"
FT   CARBOHYD        206
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00498"
FT   DISULFID        38..158
FT                   /evidence="ECO:0000305|PubMed:8288603"
FT   DISULFID        74..90
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   DISULFID        205..227
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   DISULFID        238..268
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
SQ   SEQUENCE   309 AA;  34265 MW;  014F0B5F2BD56FDB CRC64;
     MDISFLVFIT LSMALFSSNV TGTSVTSRVR RGINEKHCGF RPVITRIIGG GIATPHSWPW
     MVGIFKVNPH RFLCGGSIIN KVSVVTAAHC LVTQFGNRQN YSIFVRVGAH DIDNSGTNYQ
     VDKVIVHQGY KHHSHYYDIG LILLSKPVEY NDKIQPVCIP EFNKPHVNLN NIKVVITGWG
     VTGKATEKRN VLRELELPVV TNEQCNKSYQ TLPFSKLNRG ITNDMICAGF PEGGKDACQG
     DSGGPLMYQN PTTGRVKIVG VVSFGFECAR PNFPGVYTRL SSYVNWLQEI TFGQSLASLF
     EVVPIFIPE