Clotting factor B (EC 3.4.21.85) (Coagulation factor B) [Cleaved into: Clotting factor B light chain; Clotting factor B heavy chain]

 CFB_TACTR               Reviewed;         400 AA.
 Q27081;
 18-MAY-2010, integrated into UniProtKB/Swiss-Prot.
 01-NOV-1996, sequence version 1.
 02-DEC-2020, entry version 85.
 RecName: Full=Clotting factor B {ECO:0000303|PubMed:3519594};
          EC=3.4.21.85;
 AltName: Full=Coagulation factor B {ECO:0000303|PubMed:8407978, ECO:0000312|EMBL:BAA03528.1};
 Contains:
   RecName: Full=Clotting factor B light chain {ECO:0000303|PubMed:3519594, ECO:0000303|PubMed:8407978};
 Contains:
   RecName: Full=Clotting factor B heavy chain {ECO:0000303|PubMed:3519594, ECO:0000303|PubMed:8407978};
 Flags: Precursor;
 Tachypleus tridentatus (Japanese horseshoe crab).
 Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Merostomata;
 Xiphosura; Limulidae; Tachypleus.
 NCBI_TaxID=6853;
 [1] {ECO:0000305, ECO:0000312|EMBL:BAA03528.1}
 NUCLEOTIDE SEQUENCE [MRNA], PROTEIN SEQUENCE OF 24-44; 49-53; 55-61; 63-68;
 127-136; 148-150; 152-158; 162-185; 187-247; 274-280; 307-313; 322-337;
 368-373; 376-378; 380-385 AND 391-400, AND PROTEOLYTIC PROCESSING.
 TISSUE=Hemocyte {ECO:0000269|PubMed:8407978};
 PubMed=8407978;
 Muta T., Oda T., Iwanaga S.;
 "Horseshoe crab coagulation factor B. A unique serine protease zymogen
 activated by cleavage of an Ile-Ile bond.";
 J. Biol. Chem. 268:21384-21388(1993).
 [2] {ECO:0000305}
 FUNCTION, ACTIVITY REGULATION, BIOPHYSICOCHEMICAL PROPERTIES, AND SUBUNIT.
 PubMed=3519594; DOI=10.1093/oxfordjournals.jbchem.a135545;
 Nakamura T., Horiuchi T., Morita T., Iwanaga S.;
 "Purification and properties of intracellular clotting factor, factor B,
 from horseshoe crab (Tachypleus tridentatus) hemocytes.";
 J. Biochem. 99:847-857(1986).
 [3] {ECO:0000305}
 FUNCTION, AND CATALYTIC ACTIVITY.
 PubMed=2266134;
 Muta T., Hashimoto R., Miyata T., Nishimura H., Toh Y., Iwanaga S.;
 "Proclotting enzyme from horseshoe crab hemocytes. cDNA cloning, disulfide
 locations, and subcellular localization.";
 J. Biol. Chem. 265:22426-22433(1990).
 -!- FUNCTION: This enzyme is closely associated with an endotoxin-sensitive
     hemolymph coagulation system which may play important roles in both
     hemostasis and host defense mechanisms. Its active form catalyzes the
     activation of proclotting enzyme. Does not activate the mammalian
     coagulation factors factor IX, factor X, prothrombin, plasminogen,
     protein C or prekallikrein. Does not hydrolyze fibrinogen. Does not
     catalyze the activation of factor C or coagulogen.
     {ECO:0000269|PubMed:2266134, ECO:0000269|PubMed:3519594}.
 -!- CATALYTIC ACTIVITY:
     Reaction=Selective cleavage of 98-Arg-|-Ile-99 bond in Limulus
       proclotting enzyme to form active clotting enzyme.; EC=3.4.21.85;
       Evidence={ECO:0000269|PubMed:2266134};
 -!- ACTIVITY REGULATION: Strongly inhibited by alpha2-plasmin inhibitor and
     DFP. Partially inhibited by benzamidine, leupeptin and PCMB.
     {ECO:0000269|PubMed:3519594}.
 -!- BIOPHYSICOCHEMICAL PROPERTIES:
     Kinetic parameters:
       Vmax=0.9 umol/min/mg enzyme toward Boc-Val-Pro-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=0.1 umol/min/mg enzyme toward Boc-Ile-Glu-Gly-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=0.2 umol/min/mg enzyme toward Boc-Leu-Ser-Thr-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=0.1 umol/min/mg enzyme toward Boc-Leu-Gly-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=1.1 umol/min/mg enzyme toward Bz-Thr-Ser-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=0.7 umol/min/mg enzyme toward Bz-Ser-Ser-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=1.3 umol/min/mg enzyme toward Bz-Ser-Thr-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=1.9 umol/min/mg enzyme toward Bz-Thr-Thr-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=1.1 umol/min/mg enzyme toward Boc-Leu-Thr-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=2.1 umol/min/mg enzyme toward Boc-Met-Thr-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=1.2 umol/min/mg enzyme toward Boc-Gln-Arg-Arg-MCA
       {ECO:0000269|PubMed:3519594};
       Vmax=0.6 umol/min/mg enzyme toward Boc-Asp-Pro-Arg-MCA
       {ECO:0000269|PubMed:3519594};
 -!- SUBUNIT: Upon activation by factor C, it is converted to a two-chain
     active form composed of a light and a heavy chain linked by a disulfide
     bond. {ECO:0000269|PubMed:3519594}.
 -!- SUBCELLULAR LOCATION: Secreted {ECO:0000305}. Note=Secreted in
     hemolymph. {ECO:0000305}.
 -!- DOMAIN: The clip domain consists of 35-55 residues which are 'knitted'
     together usually by 3 conserved disulfide bonds forming a clip-like
     compact structure. {ECO:0000255|PROSITE-ProRule:PRU01236}.
 -!- SIMILARITY: Belongs to the peptidase S1 family. CLIP subfamily.
     {ECO:0000255|PROSITE-ProRule:PRU01236}.
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 EMBL; D14701; BAA03528.1; -; mRNA.
 PIR; A48050; A48050.
 SMR; Q27081; -.
 MEROPS; S01.220; -.
 KEGG; ag:BAA03528; -.
 GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
 GO; GO:0004175; F:endopeptidase activity; IDA:UniProtKB.
 GO; GO:0004252; F:serine-type endopeptidase activity; IEA:InterPro.
 GO; GO:0042381; P:hemolymph coagulation; IDA:UniProtKB.
 GO; GO:0016485; P:protein processing; IDA:UniProtKB.
 CDD; cd00190; Tryp_SPc; 1.
 Gene3D; 2.40.10.10; -; 1.
 InterPro; IPR022700; CLIP.
 InterPro; IPR009003; Peptidase_S1_PA.
 InterPro; IPR043504; Peptidase_S1_PA_chymotrypsin.
 InterPro; IPR001314; Peptidase_S1A.
 InterPro; IPR001254; Trypsin_dom.
 InterPro; IPR033116; TRYPSIN_SER.
 Pfam; PF00089; Trypsin; 1.
 PRINTS; PR00722; CHYMOTRYPSIN.
 SMART; SM00680; CLIP; 1.
 SMART; SM00020; Tryp_SPc; 1.
 SUPFAM; SSF50494; SSF50494; 1.
 PROSITE; PS51888; CLIP; 1.
 PROSITE; PS50240; TRYPSIN_DOM; 1.
 PROSITE; PS00135; TRYPSIN_SER; 1.
 1: Evidence at protein level;
 Direct protein sequencing; Disulfide bond; Glycoprotein;
 Hemolymph clotting; Hydrolase; Protease; Secreted; Serine protease; Signal;
 Zymogen.
 SIGNAL          1..23
                 /evidence="ECO:0000269|PubMed:8407978"
 CHAIN           24..103
                 /note="Clotting factor B light chain"
                 /evidence="ECO:0000269|PubMed:8407978"
                 /id="PRO_0000394311"
 PROPEP          104..124
                 /note="Activation peptide"
                 /evidence="ECO:0000269|PubMed:8407978"
                 /id="PRO_0000394312"
 CHAIN           125..400
                 /note="Clotting factor B heavy chain"
                 /evidence="ECO:0000269|PubMed:8407978"
                 /id="PRO_0000394313"
 DOMAIN          36..80
                 /note="Clip"
                 /evidence="ECO:0000255|PROSITE-ProRule:PRU01236"
 DOMAIN          148..392
                 /note="Peptidase S1"
                 /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
 ACT_SITE        192
                 /note="Charge relay system"
                 /evidence="ECO:0000250|UniProtKB:P26262"
 ACT_SITE        240
                 /note="Charge relay system"
                 /evidence="ECO:0000250|UniProtKB:P26262"
 ACT_SITE        344
                 /note="Charge relay system"
                 /evidence="ECO:0000250|UniProtKB:P26262"
 CARBOHYD        140
                 /note="N-linked (GlcNAc...) asparagine"
                 /evidence="ECO:0000255"
 CARBOHYD        251
                 /note="N-linked (GlcNAc...) asparagine"
                 /evidence="ECO:0000255"
 CARBOHYD        352
                 /note="N-linked (GlcNAc...) asparagine"
                 /evidence="ECO:0000255"
 DISULFID        37..79
                 /evidence="ECO:0000255|PROSITE-ProRule:PRU01236"
 DISULFID        47..68
                 /evidence="ECO:0000255|PROSITE-ProRule:PRU01236"
 DISULFID        53..80
                 /evidence="ECO:0000255|PROSITE-ProRule:PRU01236"
 DISULFID        307..329
                 /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
 DISULFID        340..368
                 /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
 SEQUENCE   400 AA;  43049 MW;  E71D4D808543C85B CRC64;
 MTWICVITLF ALASATLGNK VSRVGVLFPK TRNDNECTAR GGLKGSCKSL IDCPSVLATL
 KDSFPVVCSW NGRFQPIVCC PDAIAPPPVT TTAVTVISTK EPKLPRLHIS GCGKRKVKID
 ITTVGRSGSP ILPPISTPQN STGGRGIIAG GVEAKIGAWP WMAAVFVKNF GIGRFHCAGS
 IISNKYILSA AHAFLIGGRK LTPTRLAVRV GGHYIKRGQE YPVKDVIIHP HYVEKENYND
 IAIIELKEEL NFTDLVNPIC LPDPETVTDP LKDRIVTAAG WGDLDFSGPR SQVLREVSIP
 VVPVDKCDQA YEKLNTPSLK NGITNNFLCA GLEEGGKDAC QGDSGGPLML VNNTRWIVVG
 VVSFGHKCAE EGYPGVYSRV ASYLDWIAKV TNSLDHAVTN

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