P40755 (KAX22_CENMA) Reviewed, UniProtKB/Swiss-Prot

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.
Protein existence	Evidence at protein level

General annotation (Comments)

Function	Potent selective inhibitor of voltage-dependent potassium channels such as Kv1.3/KCNA3. Ref.1
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: 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 2.2

PRO_0000044904

Regions

Region

37 – 39

3

Interaction with Kv1.3 channels Potential

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 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 [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, FUNCTION. 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.
+	Additional computationally mapped references.

Cross-references

Sequence databases

PIR

A48523.

3D structure databases

PDBe
RCSB PDB
PDBj

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

ProteinModelPortal

P40755.

SMR

P40755. Positions 1-39.

ModBase

Search...

Protocols and materials databases

StructuralBiologyKnowledgebase

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:	November 16, 2011
This is version 64 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation program

Animal Toxin Annotation Program