ID   VKT_PSEPC               Reviewed;          68 AA.
AC   C0HLB2;
DT   13-FEB-2019, integrated into UniProtKB/Swiss-Prot.
DT   13-FEB-2019, sequence version 1.
DT   25-MAY-2022, entry version 10.
DE   RecName: Full=Kunitz-type serine protease inhibitor PPTI {ECO:0000305};
DE   AltName: Full=Pseudocerastes persicus trypsin inhibitor {ECO:0000303|PubMed:30452896, ECO:0000303|PubMed:30973886};
DE            Short=PPTI {ECO:0000303|PubMed:30452896, ECO:0000303|PubMed:30973886};
OS   Pseudocerastes persicus (Persian horned viper) (False horned viper).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Viperidae; Viperinae; Pseudocerastes.
OX   NCBI_TaxID=47769;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, SUBCELLULAR LOCATION, MASS SPECTROMETRY, AND
RP   PYROGLUTAMATE FORMATION AT GLU-1.
RX   PubMed=30452896; DOI=10.1016/j.abb.2018.11.017;
RA   Banijamali S.E., Amininasab M., Elmi M.M.;
RT   "Characterization of a new member of kunitz-type protein family from the
RT   venom of Persian false-horned viper, Pseudocerastes persicus.";
RL   Arch. Biochem. Biophys. 662:1-6(2019).
RN   [2]
RP   STRUCTURE BY NMR, 3D-STRUCTURE MODELING IN COMPLEX WITH TRYPSIN OR WITH THE
RP   POTASSIUM CHANNEL KV1.1/KCNA1, DISULFIDE BOND, AND FUNCTION.
RX   PubMed=30973886; DOI=10.1371/journal.pone.0214657;
RA   Banijamali S.E., Amininasab M., Zaeifi D.;
RT   "Structural characterization of PPTI, a kunitz-type protein from the venom
RT   of Pseudocerastes persicus.";
RL   PLoS ONE 14:E0214657-E0214657(2019).
CC   -!- FUNCTION: Serine protease inhibitor that weakly inhibits trypsin
CC       (Ki=0.2 uM) (PubMed:30452896). May have potassium channel blocking
CC       activities (PubMed:30973886). {ECO:0000269|PubMed:30452896,
CC       ECO:0000305|PubMed:30973886}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:30452896}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:30452896}.
CC   -!- MASS SPECTROMETRY: Mass=7642.5; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:30452896};
CC   -!- SIMILARITY: Belongs to the venom Kunitz-type family. {ECO:0000305}.
CC   -!- WEB RESOURCE: Name=Biological Magnetic Resonance Data Bank;
CC       URL="http://www.bmrb.wisc.edu/data_library/summary/index.php?bmrbId=36197";
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DR   PDB; 6A5I; NMR; -; A=1-68.
DR   PDBsum; 6A5I; -.
DR   AlphaFoldDB; C0HLB2; -.
DR   SMR; C0HLB2; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0015459; F:potassium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   CDD; cd00109; KU; 1.
DR   Gene3D; 4.10.410.10; -; 1.
DR   InterPro; IPR002223; Kunitz_BPTI.
DR   InterPro; IPR036880; Kunitz_BPTI_sf.
DR   InterPro; IPR020901; Prtase_inh_Kunz-CS.
DR   Pfam; PF00014; Kunitz_BPTI; 1.
DR   PRINTS; PR00759; BASICPTASE.
DR   SMART; SM00131; KU; 1.
DR   SUPFAM; SSF57362; SSF57362; 1.
DR   PROSITE; PS00280; BPTI_KUNITZ_1; 1.
DR   PROSITE; PS50279; BPTI_KUNITZ_2; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Direct protein sequencing; Disulfide bond;
KW   Ion channel impairing toxin; Potassium channel impairing toxin;
KW   Protease inhibitor; Pyrrolidone carboxylic acid; Secreted;
KW   Serine protease inhibitor; Toxin;
KW   Voltage-gated potassium channel impairing toxin.
FT   CHAIN           1..68
FT                   /note="Kunitz-type serine protease inhibitor PPTI"
FT                   /id="PRO_0000446256"
FT   DOMAIN          7..57
FT                   /note="BPTI/Kunitz inhibitor"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT   SITE            5
FT                   /note="May be the major determinant of the binding affinity
FT                   for potassium channels"
FT                   /evidence="ECO:0000305|PubMed:30973886"
FT   SITE            17..18
FT                   /note="Reactive bond for trypsin"
FT                   /evidence="ECO:0000250|UniProtKB:P31713,
FT                   ECO:0000305|PubMed:30973886"
FT   MOD_RES         1
FT                   /note="Pyrrolidone carboxylic acid (Glu)"
FT                   /evidence="ECO:0000269|PubMed:30452896"
FT   DISULFID        7..57
FT                   /evidence="ECO:0000269|PubMed:30973886,
FT                   ECO:0007744|PDB:6A5I"
FT   DISULFID        16..40
FT                   /evidence="ECO:0000269|PubMed:30973886,
FT                   ECO:0007744|PDB:6A5I"
FT   DISULFID        32..53
FT                   /evidence="ECO:0000269|PubMed:30973886,
FT                   ECO:0007744|PDB:6A5I"
FT   HELIX           5..8
FT                   /evidence="ECO:0007829|PDB:6A5I"
FT   STRAND          20..26
FT                   /evidence="ECO:0007829|PDB:6A5I"
FT   HELIX           27..29
FT                   /evidence="ECO:0007829|PDB:6A5I"
FT   STRAND          31..37
FT                   /evidence="ECO:0007829|PDB:6A5I"
FT   HELIX           50..57
FT                   /evidence="ECO:0007829|PDB:6A5I"
SQ   SEQUENCE   68 AA;  7668 MW;  43DA5C90DFECAC75 CRC64;
     EDRPKFCYLP DDPGVCKAHI PRFYYNPASN KCKEFIYGGC GGNANNFETR AECRHTCVAS
     RKGGPRRP