P59847 (KAX25_CENLM) Reviewed, UniProtKB/Swiss-Prot

Names and origin

Protein names	Recommended name: Potassium channel toxin alpha-KTx 2.5 Alternative name(s): Hongotoxin-1 Short name=HgTX1
Organism	Centruroides limbatus (Bark scorpion)
Taxonomic identifier	244936 [NCBI]
Taxonomic lineage	cellular organisms › Eukaryota › Opisthokonta › Metazoa › Eumetazoa › Bilateria › Protostomia › Ecdysozoa › Panarthropoda › Arthropoda › Chelicerata › Arachnida › Scorpiones › Buthida › Buthoidea › Buthidae › Centruroides

Protein attributes

Sequence length	39 AA.
Sequence status	Complete.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Potent selective inhibitor of Kv1.1/KCNA1, Kv1.2/KCNA2, Kv1.3/KCNA3 voltage-gated potassium channels. Weak inhibitor of Kv1.6/KCNA6 potassium channel. Ref.1
Subcellular location	Secreted.
Tissue specificity	Expressed by the venom gland.
Domain	Has the structural arrangement of an alpha-helix connected to a beta-sheet by disulfide bonds (CSalpha/beta).
Miscellaneous	Does not block Kv1.4/KCNA4 and Kv1.5/KCNA5 currents (Ref.1).
Sequence similarities	Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 2 subfamily.
Mass spectrometry	Molecular mass is 4219 Da from positions 1 - 39. Determined by ESI. Ref.2

Ontologies

Keywords
Cellular component	Secreted
Molecular function	Ion channel impairing toxin Neurotoxin Potassium channel inhibitor Toxin
PTM	Disulfide bond
Technical term	3D-structure Direct protein sequencing
Gene Ontology (GO)
Biological_process	defense response Inferred from electronic annotation. Source: InterPro pathogenesis Inferred from electronic annotation. Source: InterPro
Cellular_component	extracellular region Inferred from electronic annotation. Source: UniProtKB-SubCell
Molecular_function	potassium channel inhibitor activity Inferred from electronic annotation. Source: UniProtKB-KW
Complete GO annotation...

Sequence annotation (Features)

Feature key

Position(s)

Length

Description

Graphical view

Feature identifier

Molecule processing

Peptide

1 – 39

39

Potassium channel toxin alpha-KTx 2.5

PRO_0000044903

Sites

Site

28

1

Basic residue of the functional dyad By similarity

Site

37

1

Aromatic residue of the functional dyad By similarity

Amino acid modifications

Disulfide bond

7 ↔ 29

Ref.2

Disulfide bond

13 ↔ 34

Ref.2

Disulfide bond

17 ↔ 36

Ref.2

Experimental info

Mutagenesis

19

1

A → C: No loss of activity. Ref.2

Mutagenesis

19

1

A → Y: No loss of activity; when associated with F-37. Ref.2

Mutagenesis

37

1

Y → F: No loss of activity; when associated with Y-19. Ref.2

Secondary structure

1

.

.

.

.

.

.

.

.

.

39

Helix Strand Turn

Details...

Beta strand

8 – 10

3

Helix

11 – 13

3

Helix

14 – 20

7

Beta strand

26 – 30

5

Beta strand

33 – 37

5

Sequences

	Sequence		Length	Mass (Da)
	P59847 [UniParc]. Last modified September 19, 2003. Version 1. Checksum: B4ABC83F8EE7E637	FASTA	39	4,226
	10 20 30 TVIDVKCTSP KQCLPPCKAQ FGIRAGAKCM NGKCKCYPH

References

[1]

"Subunit composition of brain voltage-gated potassium channels determined by hongotoxin-1, a novel peptide derived from Centruroides limbatus venom." Koschak A., Bugianesi R.M., Mitterdorfer J., Kaczorowski G.J., Garcia M.L., Knaus H.-G. J. Biol. Chem. 273:2639-2644(1998) [PubMed] [Europe PMC] [Abstract] Cited for: PROTEIN SEQUENCE, FUNCTION, MUTAGENESIS. Tissue: Venom.

[2]

"Synthesis, characterization, and application of cy-dye- and alexa-dye-labeled hongotoxin(1) analogues. The first high affinity fluorescence probes for voltage-gated K+ channels." Pragl B., Koschak A., Trieb M., Obermair G., Kaufmann W.A., Gerster U., Blanc E., Hahn C., Prinz H., Schuetz G., Darbon H., Gruber H.J., Knaus H.-G. Bioconj. Chem. 13:416-425(2002) [PubMed] [Europe PMC] [Abstract] Cited for: STRUCTURE BY NMR, DISULFIDE BONDS, MASS SPECTROMETRY, MUTAGENESIS OF ALA-19 AND TYR-37. Tissue: Venom.

Cross-references

3D structure databases

PDBe
RCSB PDB
PDBj

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1HLY	NMR	-	A	1-39	[»]

ProteinModelPortal

P59847.

SMR

P59847. Positions 1-39.

ModBase

Search...

Protocols and materials databases

StructuralBiologyKnowledgebase

Search...

Family and domain databases

Gene3D

3.30.30.10. 1 hit.

InterPro

IPR003614. Scorpion_toxin-like.
IPR001947. Scorpion_toxinS_K_inh.
[Graphical view]

Pfam

PF00451. Toxin_2. 1 hit.
[Graphical view]

PRINTS

PR00286. CHARYBDTOXIN.

ProDom

PD003586. Scorpion_toxinS. 1 hit.
[Graphical view] [Entries sharing at least one domain]

SUPFAM

SSF57095. SSF57095. 1 hit.

PROSITE

PS01138. SCORP_SHORT_TOXIN. 1 hit.
[Graphical view]

ProtoNet

Search...

Other

EvolutionaryTrace

P59847.

Entry information

Entry name

KAX25_CENLM

Accession

Primary (citable) accession number: P59847

Entry history

Integrated into UniProtKB/Swiss-Prot:	September 19, 2003
Last sequence update:	September 19, 2003
Last modified:	May 29, 2013
This is version 56 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Animal Toxin Annotation Program