Reviewed, UniProtKB/Swiss-Prot P45628 (KAX12_LEIQH)

Names and origin

Protein names	Recommended name:     Potassium channel toxin alpha-KTx 1.2 Alternative name(s):     Charybdotoxin-2     ChTX-Lq2     ChTx-d     Toxin 18-2     Lqh 18-2
Organism	Leiurus quinquestriatus hebraeus (Yellow scorpion)
Taxonomic identifier	6884 [NCBI]
Taxonomic lineage	Eukaryota › Metazoa › Arthropoda › Chelicerata › Arachnida › Scorpiones › Buthida › Buthoidea › Buthidae › Leiurus

Protein attributes

Sequence length	59 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	Has a potent presynaptic facilitatory action, with less effect on direct muscle stimulation. Blocks calcium-activated potassium channels.
Subcellular location	Secreted.
Tissue specificity	Expressed by the venom gland.
Sequence similarities	Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 1 subfamily.

Ontologies

Keywords
Cellular component	Secreted
Domain	Signal
Molecular function	Ionic channel inhibitor Neurotoxin Potassium channel inhibitor Toxin
PTM	Disulfide bond Pyrrolidone carboxylic acid
Technical term	3D-structure Direct protein sequencing
Gene Ontology (GO)
Biological process	pathogenesis Inferred from electronic annotation. Source: UniProtKB-KW
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

Signal peptide

1 – 22

22

Ref.2

Chain

23 – 59

37

Potassium channel toxin alpha-KTx 1.2

PRO_0000035309

Regions

Region

48 – 55

8

Interaction with Ca(2+)-activated K(+) channels Potential

Amino acid modifications

Modified residue

23

1

Pyrrolidone carboxylic acid

Disulfide bond

29 ↔ 50

Ref.5

Disulfide bond

35 ↔ 55

Ref.5

Disulfide bond

39 ↔ 57

Ref.5

Secondary structure

1

.

.

.

.

.

.

.

59

Helix Strand Turn

Details...

Helix

32 – 43

12

Beta strand

48 – 51

4

Beta strand

54 – 57

4

Sequences

	Sequence		Length	Mass (Da)
	P45628-1 [UniParc]. Last modified November 21, 2003. Version 2. Checksum: C1DBB5F32A19E3C8	FASTA	59	6,772
	10 20 30 40 50 MKILSVLLLA LIICSIIDWS EGQFTQESCT ASNQCWSICK RLHNTNRGKC MNKKCRCYS

References

[1]	"Dynamic diversification from a putative common ancestor of scorpion toxins affecting sodium, potassium, and chloride channels." Froy O., Sagiv T., Poreh M., Urbach D., Zilberberg N., Gurevitz M. J. Mol. Evol. 48:187-196(1999) [PubMed: 9929387] [Abstract] Cited for: NUCLEOTIDE SEQUENCE [GENOMIC DNA]. Tissue: Single abdominal segment.
[2]	"Analysis of the blocking activity of charybdotoxin homologs and iodinated derivatives against Ca2+-activated K+ channels." Lucchesi K., Ravindran A., Young H., Moczydlowski E. J. Membr. Biol. 109:269-281(1989) [PubMed: 2477548] [Abstract] Cited for: PROTEIN SEQUENCE OF 23-59. Tissue: Venom.
[3]	"Neuromuscular effects of some potassium channel blocking toxins from the venom of the scorpion Leiurus quinquestriatus hebreus." Marshall D.L., Vatanpour H., Harvey A.L., Boyot P., Pinkasfeld S., Doljansky Y., Bouet F., Menez A. Toxicon 32:1433-1443(1994) [PubMed: 7533951] [Abstract] Cited for: PROTEIN SEQUENCE OF 28-59. Tissue: Venom.
[4]	"Moving pieces in a taxonomic puzzle: venom 2D-LC/MS and data clustering analyses to infer phylogenetic relationships in some scorpions from the Buthidae family (Scorpiones)." Nascimento D.G., Rates B., Santos D.M., Verano-Braga T., Barbosa-Silva A., Dutra A.A.A., Biondi I., Martin-Eauclaire M.-F., De Lima M.E., Pimenta A.M.C. Toxicon 47:628-639(2006) [PubMed: 16551474] [Abstract] Cited for: IDENTIFICATION BY MASS SPECTROMETRY.
[5]	"Solution structure of potassium channel-inhibiting scorpion toxin Lq2." Renisio J.-G., Lu Z., Blanc E., Jin W., Lewis J.H., Bornet O., Darbon H. Proteins 34:417-426(1999) [PubMed: 10081954] [Abstract] Cited for: STRUCTURE BY NMR, DISULFIDE BONDS.

Cross-references

Sequence databases

PIR

B60963.

3D structure databases

PDBPDBe

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1LIR	NMR	-	A	24-59	[»]

ModBase

Search...

Family and domain databases

InterPro

IPR001947. Scorpion_toxinS.
[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]

PROSITE

PS01138. SCORP_SHORT_TOXIN. 1 hit.
[Graphical view]

ProtoNet

Search...

Entry information

Entry name

KAX12_LEIQH

Accession

Primary (citable) accession number: P45628

Entry history

Integrated into UniProtKB/Swiss-Prot:	November 1, 1995
Last sequence update:	November 21, 2003
Last modified:	June 16, 2009
This is version 75 of the entry and version 2 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

Tox-Prot (Toxin Annotation Project)