ID   BLTX_BLABR              Reviewed;         282 AA.
AC   Q76B45;
DT   03-APR-2007, integrated into UniProtKB/Swiss-Prot.
DT   05-JUL-2004, sequence version 1.
DT   03-AUG-2022, entry version 65.
DE   RecName: Full=Blarina toxin;
DE            Short=BLTX;
DE            EC=3.4.21.-;
DE   Flags: Precursor;
GN   Name=BTX;
OS   Blarina brevicauda (Northern short-tailed shrew).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Eulipotyphla; Soricidae; Soricinae; Blarina.
OX   NCBI_TaxID=9387;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], PROTEIN SEQUENCE OF 30-54, FUNCTION, CATALYTIC
RP   ACTIVITY, ACTIVITY REGULATION, BIOPHYSICOCHEMICAL PROPERTIES, AND TOXIC
RP   DOSE.
RC   TISSUE=Saliva, and Salivary gland;
RX   PubMed=15136743; DOI=10.1073/pnas.0402517101;
RA   Kita M., Nakamura Y., Okumura Y., Ohdachi S.D., Oba Y., Yoshikuni M.,
RA   Kido H., Uemura D.;
RT   "Blarina toxin, a mammalian lethal venom from the short-tailed shrew
RT   Blarina brevicauda: isolation and characterization.";
RL   Proc. Natl. Acad. Sci. U.S.A. 101:7542-7547(2004).
CC   -!- FUNCTION: Has kallikrein-like activity, converts kininogens to kinins,
CC       and has dilatory effects on the blood vessel walls. Shows highest
CC       activity toward Pro-Phe-Arg-MCA and Boc-Val-Leu-Lys-MCA in vitro. Has
CC       preference for Arg and Lys in position P1 and hydrophobic residues in
CC       position P2. {ECO:0000269|PubMed:15136743}.
CC   -!- ACTIVITY REGULATION: Strongly inhibited by aprotinin, moderately
CC       inhibited by secretory leukoprotease inhibitor, the Kunitz-type soybean
CC       trypsin inhibitor, and leupeptin, and not inhibited by urinary trypsin
CC       inhibitor or alpha-1 protease inhibitor. {ECO:0000269|PubMed:15136743}.
CC   -!- BIOPHYSICOCHEMICAL PROPERTIES:
CC       pH dependence:
CC         Optimum pH is 9.0. {ECO:0000269|PubMed:15136743};
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- TISSUE SPECIFICITY: Submaxillary and sublingual salivary glands.
CC   -!- TOXIC DOSE: LD(50) is 1 mg/kg by intraperitoneal injection into mice.
CC       This injection causes irregular respiration, paralysis, convulsions and
CC       death. {ECO:0000269|PubMed:15136743}.
CC   -!- SIMILARITY: Belongs to the peptidase S1 family. Kallikrein subfamily.
CC       {ECO:0000255|PROSITE-ProRule:PRU00274}.
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DR   EMBL; AB111919; BAD18893.1; -; mRNA.
DR   AlphaFoldDB; Q76B45; -.
DR   SMR; Q76B45; -.
DR   MEROPS; S01.409; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0004252; F:serine-type endopeptidase activity; IEA:InterPro.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0006508; P:proteolysis; IEA:UniProtKB-KW.
DR   CDD; cd00190; Tryp_SPc; 1.
DR   Gene3D; 2.40.10.10; -; 2.
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; Hydrolase;
KW   Protease; Secreted; Serine protease; Signal; Toxin; Zymogen.
FT   SIGNAL          1..17
FT                   /evidence="ECO:0000255"
FT   PROPEP          18..29
FT                   /note="Activation peptide"
FT                   /evidence="ECO:0000269|PubMed:15136743"
FT                   /id="PRO_0000283773"
FT   CHAIN           30..282
FT                   /note="Blarina toxin"
FT                   /id="PRO_0000283774"
FT   DOMAIN          30..279
FT                   /note="Peptidase S1"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   ACT_SITE        72
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000250"
FT   ACT_SITE        138
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000250"
FT   ACT_SITE        234
FT                   /note="Charge relay system"
FT                   /evidence="ECO:0000250"
FT   CARBOHYD        100
FT                   /note="O-linked (GalNAc...) serine"
FT                   /evidence="ECO:0000250"
FT   CARBOHYD        109
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   CARBOHYD        122
FT                   /note="N-linked (GlcNAc...) asparagine"
FT                   /evidence="ECO:0000255"
FT   DISULFID        36..194
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   DISULFID        57..73
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   DISULFID        170..240
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   DISULFID        205..219
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
FT   DISULFID        230..255
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00274"
SQ   SEQUENCE   282 AA;  31066 MW;  D224151DE5BB52F6 CRC64;
     MCFLLLCLTL TLAGTGAVPT GPSIEIHSRI IGGWECDKHS QPWQALLTFT RKHNSVCGGV
     LVHSQWVLTA AHCIGDNYKV LLGLHDRSSE ESTVQEARVS ARFPHPLYNM TLLNLLLSHK
     MNLTFFYKTF LGADFSHDLM LLRLDQPVQL TDAVQVLDLP TQEPQVGSTC HVSGWGRTSQ
     NYENSFVLPE KLQCVEFTLL SNNECSHAHM FKVTEAMLCA GHMEGGKDSC VGDSGGPLIC
     DGVFQGIASW GSSPCGQQGR PGIYVKVFLY ISWIQETIKA HS