Reviewed, UniProtKB/Swiss-Prot P40755 (KAX22_CENMA)

Names and origin

Protein names	Recommended name:     Potassium channel toxin alpha-KTx 2.2 Alternative name(s):     Margatoxin       Short name=MgTX
Organism	Centruroides margaritatus (Scorpion)
Taxonomic identifier	29018 [NCBI]
Taxonomic lineage	Eukaryota › Metazoa › Arthropoda › Chelicerata › Arachnida › Scorpiones › Buthida › Buthoidea › Buthidae › Centruroides

Protein attributes

Sequence length	39 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Potent selective inhibitor of voltage-dependent potassium channels such as Kv1.3.
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 2 subfamily.

Ontologies

Keywords
Cellular component	Secreted
Molecular function	Ionic channel inhibitor Neurotoxin Potassium channel inhibitor Toxin
PTM	Disulfide bond
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

Peptide

1 – 39

39

Potassium channel toxin alpha-KTx 2.2

PRO_0000044904

Regions

Region

37 – 39

3

Interaction with Kv1.3 channels Potential

Amino acid modifications

Disulfide bond

7 ↔ 29

Ref.2 Ref.3

Disulfide bond

13 ↔ 34

Ref.2 Ref.3

Disulfide bond

17 ↔ 36

Ref.2 Ref.3

Secondary structure

1

.

.

.

.

.

.

.

.

39

Helix Strand Turn

Details...

Helix

10 – 13

4

Helix

14 – 20

7

Beta strand

26 – 30

5

Beta strand

33 – 37

5

Sequences

	Sequence		Length	Mass (Da)
	P40755-1 [UniParc]. Last modified February 1, 1995. Version 1. Checksum: 0FB748318014BE0D	FASTA	39	4,185
	10 20 30 TIINVKCTSP KQCLPPCKAQ FGQSAGAKCM NGKCKCYPH

References

[1]	"Purification, characterization, and biosynthesis of margatoxin, a component of Centruroides margaritatus venom that selectively inhibits voltage-dependent potassium channels." Garcia-Calvo M., Leonard R.J., Novick J., Stevens S.P., Schmalhofer W., Kaczorowski G.J., Garcia M.L. J. Biol. Chem. 268:18866-18874(1993) [PubMed: 8360176] [Abstract] Cited for: PROTEIN SEQUENCE. Tissue: Venom.
[2]	"Chemical synthesis and structure-function studies of margatoxin, a potent inhibitor of voltage-dependent potassium channel in human T lymphocytes." Bednarek M.A., Bugianesi R.M., Leonard R.J., Felix J.P. Biochem. Biophys. Res. Commun. 198:619-625(1994) [PubMed: 8297371] [Abstract] Cited for: SYNTHESIS, DISULFIDE BONDS.
[3]	"Determination of the three-dimensional structure of margatoxin by 1H, 13C, 15N triple-resonance nuclear magnetic resonance spectroscopy." Johnson B.A., Stevens S.P., Williamson J.M. Biochemistry 33:15061-15070(1994) [PubMed: 7999764] [Abstract] Cited for: STRUCTURE BY NMR, DISULFIDE BONDS.

Cross-references

Sequence databases

PIR

A48523.

3D structure databases

PDBPDBe

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

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

KAX22_CENMA

Accession

Primary (citable) accession number: P40755

Entry history

Integrated into UniProtKB/Swiss-Prot:	February 1, 1995
Last sequence update:	February 1, 1995
Last modified:	June 16, 2009
This is version 60 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

Tox-Prot (Toxin Annotation Project)