P00987 (IVBI1_BUNMU) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names	Recommended name: Beta-bungarotoxin B1 chain, major component Alternative name(s): Beta-1-bungarotoxin
Organism	Bungarus multicinctus (Many-banded krait)
Taxonomic identifier	8616 [NCBI]
Taxonomic lineage	cellular organisms › Eukaryota › Opisthokonta › Metazoa › Eumetazoa › Bilateria › Deuterostomia › Chordata › Craniata › Vertebrata › Gnathostomata › Teleostomi › Euteleostomi › Sarcopterygii › Tetrapoda › Amniota › Sauropsida › Sauria › Lepidosauria › Squamata › Scleroglossa › Serpentes › Colubroidea › Elapidae › Bungarinae › Bungarus

Protein attributes

Sequence length	85 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is further processed into a mature form.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Beta-1-bungarotoxin is a presynaptic neurotoxin of the venom. The B chain is homologous to venom basic protease inhibitors but has no protease inhibitor activity and blocks voltage-gated potassium channels By similarity. Ref.1
Subunit structure	Heterodimer; disulfide-linked. The A chains have phospholipase A2 activity and the B chains show homology with the basic protease inhibitors. Ref.5
Subcellular location	Secreted.
Tissue specificity	Expressed by the venom gland.
Sequence similarities	Belongs to the venom Kunitz-type family. Contains 1 BPTI/Kunitz inhibitor domain.

Ontologies

Keywords
Cellular component	Secreted
Domain	Signal
Molecular function	Ion channel impairing toxin Neurotoxin Potassium channel inhibitor Presynaptic neurotoxin Toxin
PTM	Disulfide bond
Technical term	Direct protein sequencing
Gene Ontology (GO)
Cellular_component	other organism presynaptic membrane Inferred from electronic annotation. Source: UniProtKB-KW
Molecular_function	potassium channel inhibitor activity Inferred from electronic annotation. Source: UniProtKB-KW serine-type endopeptidase inhibitor activity Inferred from electronic annotation. Source: InterPro
Complete GO annotation...

Sequence annotation (Features)

	Feature key	Position(s)	Length	Description	Graphical view	Feature identifier
Molecule processing
	Signal peptide	1 – 24	24	Ref.3
	Chain	25 – 85	61	Beta-bungarotoxin B1 chain, major component		PRO_0000016863
Regions
	Domain	31 – 81	51	BPTI/Kunitz inhibitor
Amino acid modifications
	Disulfide bond	31 ↔ 81		By similarity
	Disulfide bond	40 ↔ 64		By similarity
	Disulfide bond	56 ↔ 77		By similarity
	Disulfide bond	79		Interchain (with an A chain)
Experimental info
	Mutagenesis	79	1	C → S: Loss of PA2 activity. Weak loss in folding. Ref.4
	Sequence conflict	16	1	C → S in CAB62503. Ref.2
	Sequence conflict	45	1	Missing AA sequence Ref.3
	Sequence conflict	65 – 70	6	NGNGNH → DGDHGN AA sequence Ref.3

Sequences

	Sequence		Length	Mass (Da)
	P00987 [UniParc]. Last modified July 15, 1998. Version 2. Checksum: A1E3D452AE67DE5C	FASTA	85	9,571
	10 20 30 40 50 60 MSSGGLLLLL GLLTLCAELI PVSSRQRHRD CDKPPDKGNC GPVRRAFYYD TRLKTCKAFQ 70 80 YRGCNGNGNH FKTETLCRCE CLVYP

References

[1]	"Cloning and functional expression of B chains of beta-bungarotoxins from Bungarus multicinctus (Taiwan banded krait)." Wu P.-F., Wu S.-N., Chang C.-C., Chang L.-S. Biochem. J. 334:87-92(1998) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [MRNA], FUNCTION. Tissue: Venom gland.
[2]	"Genetic organization of A chain and B chain of beta-bungarotoxin from Taiwan banded krait (Bungarus multicinctus). A chain genes and B chain genes do not share a common origin." Wu P.-F., Chang L.-S. Eur. J. Biochem. 267:4668-4675(2000) [PubMed] [Europe PMC] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]. Tissue: Liver.
[3]	"Amino acid sequences of the two polypeptide chains in beta1-bungarotoxin from the venom of Bungarus multicinctus." Kondo K., Narita K., Lee C.-Y. J. Biochem. 83:101-115(1978) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE OF 25-85. Tissue: Venom.
[4]	"Expression of A chain and B chain of beta-bungarotoxin from taiwan banded krait: the functional implication of the interchain disulfide bond between A chain and B chain." Wu P.-F., Chang L.-S. J. Protein Chem. 20:413-421(2001) [PubMed] [Europe PMC] [Abstract] Cited for: MUTAGENESIS OF CYS-79.
[5]	"Divergence of genes encoding B chains of beta-bungarotoxins." Cheng Y.-C., Chen K.-C., Lin S.-K., Chang L.-S. Toxicon 47:322-329(2006) [PubMed] [Europe PMC] [Abstract] Cited for: SUBUNIT. Tissue: Venom.

Cross-references

Sequence databases
EMBL GenBank DDBJ	Y12100 mRNA. Translation: CAA72809.1. AJ251223 Genomic DNA. Translation: CAB62503.1.
PIR	TIKFBY. A01219.
3D structure databases
ProteinModelPortal	P00987.
SMR	P00987. Positions 25-84.
ModBase	Search...
Protocols and materials databases
StructuralBiologyKnowledgebase	Search...
Family and domain databases
Gene3D	4.10.410.10. 1 hit.
InterPro	IPR002223. Prot_inh_Kunz-m. IPR020901. Prtase_inh_Kunz-CS. [Graphical view]
Pfam	PF00014. Kunitz_BPTI. 1 hit. [Graphical view]
PRINTS	PR00759. BASICPTASE.
SMART	SM00131. KU. 1 hit. [Graphical view]
SUPFAM	SSF57362. Prot_inh_Kunz-m. 1 hit.
PROSITE	PS00280. BPTI_KUNITZ_1. 1 hit. PS50279. BPTI_KUNITZ_2. 1 hit. [Graphical view]
ProtoNet	Search...

Entry information

Entry name

IVBI1_BUNMU

Accession

Primary (citable) accession number: P00987
Secondary accession number(s): O42298, P00988, Q9PTA4

Entry history

Integrated into UniProtKB/Swiss-Prot:	July 21, 1986
Last sequence update:	July 15, 1998
Last modified:	April 3, 2013
This is version 82 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Animal Toxin Annotation Program

Annotation program

Chordata Protein Annotation Program