VKTH2_BUNMU
ID VKTH2_BUNMU Reviewed; 85 AA.
AC P00989; O42299; Q1RPT1; Q9PRV8; Q9PTA3;
DT 21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT 15-JUL-1998, sequence version 2.
DT 25-MAY-2022, entry version 136.
DE RecName: Full=Kunitz-type serine protease inhibitor homolog beta-bungarotoxin B2 chain;
DE AltName: Full=Beta-2-bungarotoxin;
DE Flags: Precursor;
OS Bungarus multicinctus (Many-banded krait).
OC Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC Serpentes; Colubroidea; Elapidae; Bungarinae; Bungarus.
OX NCBI_TaxID=8616;
RN [1]
RP NUCLEOTIDE SEQUENCE [MRNA], AND FUNCTION.
RC TISSUE=Venom gland;
RX PubMed=9693106; DOI=10.1042/bj3340087;
RA Wu P.-F., Wu S.-N., Chang C.-C., Chang L.-S.;
RT "Cloning and functional expression of B chains of beta-bungarotoxins from
RT Bungarus multicinctus (Taiwan banded krait).";
RL Biochem. J. 334:87-92(1998).
RN [2]
RP NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC TISSUE=Venom gland;
RX PubMed=16457863; DOI=10.1016/j.toxicon.2005.11.009;
RA Cheng Y.-C., Chen K.-C., Lin S.-K., Chang L.-S.;
RT "Divergence of genes encoding B chains of beta-bungarotoxins.";
RL Toxicon 47:322-329(2006).
RN [3]
RP NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 1-82.
RC TISSUE=Liver;
RX PubMed=10903499; DOI=10.1046/j.1432-1327.2000.01518.x;
RA Wu P.-F., Chang L.-S.;
RT "Genetic organization of A chain and B chain of beta-bungarotoxin from
RT Taiwan banded krait (Bungarus multicinctus). A chain genes and B chain
RT genes do not share a common origin.";
RL Eur. J. Biochem. 267:4668-4675(2000).
RN [4]
RP PROTEIN SEQUENCE OF 25-85.
RC TISSUE=Venom;
RX PubMed=7096304; DOI=10.1093/oxfordjournals.jbchem.a133843;
RA Kondo K., Toda H., Narita K., Lee C.-Y.;
RT "Amino acid sequence of beta 2-bungarotoxin from Bungarus multicinctus
RT venom. The amino acid substitutions in the B chains.";
RL J. Biochem. 91:1519-1530(1982).
RN [5]
RP PROTEIN SEQUENCE OF 25-63.
RX PubMed=7945237; DOI=10.1042/bj3030171;
RA Chu C.C., Chu S.T., Chen S.W., Chen Y.H.;
RT "The non-phospholipase A2 subunit of beta-bungarotoxin plays an important
RT role in the phospholipase A2-independent neurotoxic effect:
RT characterization of three isotoxins with a common phospholipase A2
RT subunit.";
RL Biochem. J. 303:171-176(1994).
RN [6]
RP X-RAY CRYSTALLOGRAPHY (2.45 ANGSTROMS), AND DISULFIDE BONDS.
RC TISSUE=Venom;
RX PubMed=8590005; DOI=10.1016/s0969-2126(01)00246-5;
RA Kwong P.D., McDonald N.Q., Sigler P.B., Hendrickson W.A.;
RT "Structure of beta 2-bungarotoxin: potassium channel binding by Kunitz
RT modules and targeted phospholipase action.";
RL Structure 3:1109-1119(1995).
CC -!- FUNCTION: Beta-2-bungarotoxin is a presynaptic neurotoxin of the venom.
CC The B chain is homologous to venom basic protease inhibitors but has no
CC protease inhibitor activity and blocks voltage-gated potassium channels
CC (Kv). {ECO:0000269|PubMed:9693106}.
CC -!- SUBUNIT: Heterodimer; disulfide-linked. The A chains have phospholipase
CC A2 activity and the B chains show homology with the basic protease
CC inhibitors. {ECO:0000269|PubMed:8590005}.
CC -!- SUBCELLULAR LOCATION: Secreted.
CC -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC -!- SIMILARITY: Belongs to the venom Kunitz-type family. {ECO:0000305}.
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DR EMBL; Y12101; CAA72810.1; -; mRNA.
DR EMBL; AM050151; CAJ18318.1; -; Genomic_DNA.
DR EMBL; AJ251224; CAB62504.1; -; Genomic_DNA.
DR PIR; A44550; TIKFB2.
DR PDB; 1BUN; X-ray; 2.45 A; B=25-85.
DR PDBsum; 1BUN; -.
DR AlphaFoldDB; P00989; -.
DR SMR; P00989; -.
DR MINT; P00989; -.
DR PRIDE; P00989; -.
DR EvolutionaryTrace; P00989; -.
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:InterPro.
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; Neurotoxin; Potassium channel impairing toxin;
KW Presynaptic neurotoxin; Secreted; Signal; Toxin;
KW Voltage-gated potassium channel impairing toxin.
FT SIGNAL 1..24
FT /evidence="ECO:0000269|PubMed:7096304,
FT ECO:0000269|PubMed:7945237"
FT CHAIN 25..85
FT /note="Kunitz-type serine protease inhibitor homolog beta-
FT bungarotoxin B2 chain"
FT /id="PRO_0000016864"
FT DOMAIN 31..81
FT /note="BPTI/Kunitz inhibitor"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031"
FT DISULFID 31..81
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031,
FT ECO:0000269|PubMed:8590005"
FT DISULFID 40..64
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031,
FT ECO:0000269|PubMed:8590005"
FT DISULFID 56..77
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031,
FT ECO:0000269|PubMed:8590005"
FT DISULFID 79
FT /note="Interchain (with an A chain)"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU00031,
FT ECO:0000269|PubMed:8590005"
FT CONFLICT 44
FT /note="Missing (in Ref. 4; AA sequence)"
FT /evidence="ECO:0000305"
FT CONFLICT 65..70
FT /note="NGNGNH -> DGDHGN (in Ref. 4; AA sequence)"
FT /evidence="ECO:0000305"
FT CONFLICT 82..83
FT /note="LE -> EL (in Ref. 4; AA sequence)"
FT /evidence="ECO:0000305"
FT TURN 29..32
FT /evidence="ECO:0007829|PDB:1BUN"
FT STRAND 40..42
FT /evidence="ECO:0007829|PDB:1BUN"
FT STRAND 44..50
FT /evidence="ECO:0007829|PDB:1BUN"
FT HELIX 51..53
FT /evidence="ECO:0007829|PDB:1BUN"
FT STRAND 55..61
FT /evidence="ECO:0007829|PDB:1BUN"
FT STRAND 66..68
FT /evidence="ECO:0007829|PDB:1BUN"
FT STRAND 71..73
FT /evidence="ECO:0007829|PDB:1BUN"
FT HELIX 74..81
FT /evidence="ECO:0007829|PDB:1BUN"
SQ SEQUENCE 85 AA; 9568 MW; FE95A59AF92BF2AA CRC64;
MSSGGLLLLL GLLTLCAELT PVSSRKRHPD CDKPPDTKIC QTVVRAFYYK PSAKRCVQFR
YGGCNGNGNH FKSDHLCRCE CLEYR
