ID PA2B1_BUNMU Reviewed; 147 AA. AC P00617; Q546H2; Q8AXW1; Q8QFN8; Q9PU95; Q9PU98; DT 21-JUL-1986, integrated into UniProtKB/Swiss-Prot. DT 19-SEP-2002, sequence version 2. DT 04-NOV-2026, entry version 155. DE RecName: Full=Basic phospholipase A2 beta-bungarotoxin A1 chain; DE Short=Beta-BuTX A1 chain; DE Short=svPLA2; DE EC=3.1.1.4; DE AltName: Full=Phosphatidylcholine 2-acylhydrolase; 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] {ECO:0000312|EMBL:CAD24464.1, ECO:0000312|EMBL:CAD24465.1} RP NUCLEOTIDE SEQUENCE [GENOMIC DNA]. RC TISSUE=Liver; RX PubMed=12368113; DOI=10.1016/s0041-0101(02)00160-5; RA Chu Y.P., Chang L.S.; RT "The organization of the genes encoding the A chains of beta-bungarotoxins: RT evidence for the skipping of exon."; RL Toxicon 40:1437-1443(2002). RN [2] {ECO:0000312|EMBL:CAD24466.1} RP NUCLEOTIDE SEQUENCE [MRNA]. RC TISSUE=Venom gland; RA Chang L.-S., Chu Y.P.; RT "Genomic organization of the genes encoding the A chains of beta- RT bungarotoxins."; RL Submitted (FEB-2002) to the EMBL/GenBank/DDBJ databases. RN [3] {ECO:0000312|EMBL:CAB62164.1} RP NUCLEOTIDE SEQUENCE [GENOMIC DNA] OF 10-147. 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] {ECO:0000312|EMBL:CAB62383.1} RP NUCLEOTIDE SEQUENCE [MRNA] OF 11-147, AND MUTAGENESIS OF CYS-42. RC TISSUE=Venom gland; RX PubMed=11732693; DOI=10.1023/a:1012237005574; RA Wu P.-F., Chang L.-S.; RT "Expression of A chain and B chain of beta-bungarotoxin from taiwan banded RT krait: the functional implication of the interchain disulfide bond between RT A chain and B chain."; RL J. Protein Chem. 20:413-421(2001). RN [5] RP PROTEIN SEQUENCE OF 28-147, AND SUBCELLULAR LOCATION. RC TISSUE=Venom; RX PubMed=624701; DOI=10.1093/oxfordjournals.jbchem.a131881; RA Kondo K., Narita K., Lee C.-Y.; RT "Amino acid sequences of the two polypeptide chains in beta1-bungarotoxin RT from the venom of Bungarus multicinctus."; RL J. Biochem. 83:101-115(1978). RN [6] RP PROTEIN SEQUENCE OF 28-147, SEQUENCE REVISION TO 112-114 AND 136, RP SUBCELLULAR LOCATION, AND TOXIC DOSE. 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 [7] RP CHARACTERIZATION OF PHOSPHOLIPASE A2 ACTIVITY. RX PubMed=730754; DOI=10.1093/oxfordjournals.jbchem.a132249; RA Kondo K., Toda H., Narita K.; RT "Characterization of phospholipase A activity of beta1-bungarotoxin from RT Bungarus multicinctus venom. II. Identification of the histidine residue of RT beta1-bungarotoxin modified by p-bromophenacyl bromide."; RL J. Biochem. 84:1301-1308(1978). RN [8] RP CHARACTERIZATION OF PRESYNAPTIC NEUROTOXINS. RX PubMed=303565; DOI=10.1111/j.1432-1033.1977.tb11849.x; RA Abe T., Alema S., Miledi R.; RT "Isolation and characterization of presynaptically acting neurotoxins from RT the venom of Bungarus snakes."; RL Eur. J. Biochem. 80:1-12(1977). RN [9] RP REVIEW. RX PubMed=10936627; DOI=10.1016/s0041-0101(00)00159-8; RA Rowan E.G.; RT "What does beta-bungarotoxin do at the neuromuscular junction?"; RL Toxicon 39:107-118(2001). RN [10] RP X-RAY CRYSTALLOGRAPHY IN COMPLEX WITH CALCIUM ION, COFACTOR, AND DISULFIDE RP 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: Snake venom phospholipase A2 (PLA2) that inhibits CC neuromuscular transmission by blocking acetylcholine release from the CC nerve termini. PLA2 catalyzes the calcium-dependent hydrolysis of the CC 2-acyl groups in 3-sn-phosphoglycerides. CC -!- CATALYTIC ACTIVITY: CC Reaction=a 1,2-diacyl-sn-glycero-3-phosphocholine + H2O = a 1-acyl-sn- CC glycero-3-phosphocholine + a fatty acid + H(+); Xref=Rhea:RHEA:15801, CC ChEBI:CHEBI:15377, ChEBI:CHEBI:15378, ChEBI:CHEBI:28868, CC ChEBI:CHEBI:57643, ChEBI:CHEBI:58168; EC=3.1.1.4; CC Evidence={ECO:0000255|PROSITE-ProRule:PRU10035, ECO:0000255|PROSITE- CC ProRule:PRU10036}; CC -!- COFACTOR: CC Name=Ca(2+); Xref=ChEBI:CHEBI:29108; CC Evidence={ECO:0000305|PubMed:8590005}; CC Note=Binds 1 Ca(2+) ion. {ECO:0000305|PubMed:8590005}; 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. The A1 chain is found in beta-1 and beta-2 bungarotoxins. CC {ECO:0000269|PubMed:8590005}. CC -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:624701, CC ECO:0000269|PubMed:7096304}. CC -!- TISSUE SPECIFICITY: Expressed by the venom gland. CC {ECO:0000305|PubMed:624701, ECO:0000305|PubMed:7096304}. CC -!- TOXIC DOSE: LD(50) is 0.019 mg/kg by intraperitoneal injection into CC mice (beta-1 bungarotoxin). {ECO:0000269|PubMed:7096304}. CC -!- TOXIC DOSE: LD(50) is 0.029 mg/kg by intraperitoneal injection into CC mice (beta-2 bungarotoxin). {ECO:0000269|PubMed:7096304}. CC -!- SIMILARITY: Belongs to the phospholipase A2 family. Group I subfamily. CC D49 sub-subfamily. {ECO:0000305}. CC --------------------------------------------------------------------------- CC Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms CC Distributed under the Creative Commons Attribution (CC BY 4.0) License CC --------------------------------------------------------------------------- DR EMBL; AJ431710; CAD24465.1; -; Genomic_DNA. DR EMBL; AJ431709; CAD24464.1; -; Genomic_DNA. DR EMBL; AJ431711; CAD24466.1; -; mRNA. DR EMBL; AJ251360; CAB62164.1; -; Genomic_DNA. DR EMBL; AJ242011; CAB62383.1; -; mRNA. DR PDB; 1BUN; X-ray; 2.45 A; A=28-147. DR AlphaFoldDB; P00617; -. DR SMR; P00617; -. DR EvolutionaryTrace; P00617; -. DR GO; GO:0005576; C:extracellular region; EXP:UniProtKB. DR GO; GO:0004623; F:A2-type glycerophospholipase activity; IEA:UniProtKB-EC. DR GO; GO:0005509; F:calcium ion binding; IEA:InterPro. DR GO; GO:0005543; F:phospholipid binding; IEA:TreeGrafter. DR GO; GO:0050482; P:arachidonate secretion; IEA:InterPro. DR GO; GO:0016042; P:lipid catabolic process; IEA:InterPro. DR GO; GO:0006644; P:phospholipid metabolic process; IEA:InterPro. DR CDD; cd00125; PLA2c; 1. DR FunFam; 1.20.90.10:FF:000007; Acidic phospholipase A2; 1. DR Gene3D; 1.20.90.10; Phospholipase A2 domain; 1. DR InterPro; IPR001211; PLA2. DR InterPro; IPR016090; PLA2-like_dom. DR InterPro; IPR033112; PLA2_Asp_AS. DR InterPro; IPR033113; PLA2_histidine. DR InterPro; IPR036444; PLipase_A2_dom_sf. DR PANTHER; PTHR11716:SF100; PHOSPHOLIPASE A2; 1. DR PANTHER; PTHR11716; PHOSPHOLIPASE A2 FAMILY MEMBER; 1. DR Pfam; PF00068; Phospholip_A2_1; 1. DR PRINTS; PR00389; PHPHLIPASEA2. DR SMART; SM00085; PA2c; 1. DR SUPFAM; SSF48619; Phospholipase A2, PLA2; 1. DR PROSITE; PS00119; PA2_ASP; 1. DR PROSITE; PS00118; PA2_HIS; 1. PE 1: Evidence at protein level; KW 3D-structure; Calcium; Direct protein sequencing; Disulfide bond; KW Hydrolase; Lipid degradation; Lipid metabolism; Metal-binding; Neurotoxin; KW Presynaptic neurotoxin; Secreted; Signal; Toxin. FT SIGNAL 1..19 FT /evidence="ECO:0000255" FT PROPEP 20..27 FT /evidence="ECO:0000305|PubMed:624701, FT ECO:0000305|PubMed:7096304" FT /id="PRO_0000022835" FT CHAIN 28..147 FT /note="Basic phospholipase A2 beta-bungarotoxin A1 chain" FT /evidence="ECO:0000269|PubMed:624701, FT ECO:0000269|PubMed:7096304" FT /id="PRO_0000022836" FT ACT_SITE 75 FT /evidence="ECO:0000250|UniProtKB:P14418" FT ACT_SITE 121 FT /evidence="ECO:0000250|UniProtKB:P14418" FT BINDING 55 FT /ligand="Ca(2+)" FT /ligand_id="ChEBI:CHEBI:29108" FT /evidence="ECO:0000305|PubMed:8590005" FT BINDING 57 FT /ligand="Ca(2+)" FT /ligand_id="ChEBI:CHEBI:29108" FT /evidence="ECO:0000305|PubMed:8590005" FT BINDING 59 FT /ligand="Ca(2+)" FT /ligand_id="ChEBI:CHEBI:29108" FT /evidence="ECO:0000305|PubMed:8590005" FT BINDING 76 FT /ligand="Ca(2+)" FT /ligand_id="ChEBI:CHEBI:29108" FT /evidence="ECO:0000305|PubMed:8590005" FT DISULFID 42 FT /note="Interchain (with a B chain)" FT /evidence="ECO:0000269|PubMed:8590005" FT DISULFID 54..146 FT /evidence="ECO:0000269|PubMed:8590005, FT ECO:0007744|PDB:1BUN" FT DISULFID 56..72 FT /evidence="ECO:0000269|PubMed:8590005, FT ECO:0007744|PDB:1BUN" FT DISULFID 71..127 FT /evidence="ECO:0000269|PubMed:8590005, FT ECO:0007744|PDB:1BUN" FT DISULFID 78..120 FT /evidence="ECO:0000269|PubMed:8590005, FT ECO:0007744|PDB:1BUN" FT DISULFID 88..113 FT /evidence="ECO:0000269|PubMed:8590005, FT ECO:0007744|PDB:1BUN" FT DISULFID 106..118 FT /evidence="ECO:0000269|PubMed:8590005, FT ECO:0007744|PDB:1BUN" FT VARIANT 116 FT /note="I -> V (in 20% of the molecules)" FT MUTAGEN 42 FT /note="C->S: Loss of PA2 activity. No loss in FT Ca(2+)-binding ability. Weak loss in folding." FT /evidence="ECO:0000269|PubMed:11732693" FT CONFLICT 10 FT /note="S -> L (in Ref. 3; CAB62164)" FT /evidence="ECO:0000305" FT CONFLICT 19 FT /note="A -> S (in Ref. 1; CAD24464)" FT /evidence="ECO:0000305" FT CONFLICT 93..94 FT /note="QS -> SQ (in Ref. 5; AA sequence and 6; AA FT sequence)" FT /evidence="ECO:0000305" FT CONFLICT 130..132 FT /note="NSE -> QSD (in Ref. 5; AA sequence and 6; AA FT sequence)" FT /evidence="ECO:0000305" FT HELIX 29..37 FT /evidence="ECO:0007829|PDB:1BUN" FT HELIX 47..50 FT /evidence="ECO:0007829|PDB:1BUN" FT TURN 53..55 FT /evidence="ECO:0007829|PDB:1BUN" FT STRAND 56..58 FT /evidence="ECO:0007829|PDB:1BUN" FT HELIX 67..83 FT /evidence="ECO:0007829|PDB:1BUN" FT TURN 84..86 FT /evidence="ECO:0007829|PDB:1BUN" FT TURN 90..92 FT /evidence="ECO:0007829|PDB:1BUN" FT STRAND 97..100 FT /evidence="ECO:0007829|PDB:1BUN" FT STRAND 103..106 FT /evidence="ECO:0007829|PDB:1BUN" FT HELIX 113..130 FT /evidence="ECO:0007829|PDB:1BUN" FT HELIX 135..137 FT /evidence="ECO:0007829|PDB:1BUN" FT HELIX 142..145 FT /evidence="ECO:0007829|PDB:1BUN" SQ SEQUENCE 147 AA; 16220 MW; 12109A187E20C7F6 CRC64; MNPAHLLVLS AVCVSLLGAA NIPPHPLNLI NFMEMIRYTI PCEKTWGEYA DYGCYCGAGG SGRPIDALDR CCYVHDNCYG DAEKKHKCNP KTQSYSYKLT KRTIICYGAA GTCGRIVCDC DRTAALCFGN SEYIEGHKNI DTARFCQ //