Reviewed, UniProtKB/Swiss-Prot P80719 (KAX62_SCOMA)

Names and origin

Protein names	Recommended name:     Potassium channel toxin alpha-KTx 6.2 Alternative name(s):     Maurotoxin       Short name=MTX
Organism	Scorpio maurus palmatus (Chactoid scorpion)
Taxonomic identifier	53957 [NCBI]
Taxonomic lineage	Eukaryota › Metazoa › Arthropoda › Chelicerata › Arachnida › Scorpiones › Iurida › Scorpionoidea › Scorpionidae › Scorpioninae › Scorpio

Protein attributes

Sequence length	34 AA.
Sequence status	Complete.
Sequence processing	The displayed sequence is not processed.
Protein existence	Evidence at protein level.

General annotation (Comments)

Function	Blocks voltage-gated potassium channels (Shaker B, and Kv1.2/KCNA2). Does not block the Kv1.1/KCNA1 channel type, but is moderately active on Kv1.3/KCNA3. Also inhibits apamin-sensitive small conductance calcium-activated potassium (SK/KCNN) channels, and inhibits intermediate conductance calcium-activated potassium (KCa3.1/KCNN4) channels. Ref.1 Ref.2 Ref.4 Ref.7 Ref.8
Subcellular location	Secreted.
Tissue specificity	Expressed by the venom gland.
Toxic dose	LD50 is 4 µg/kg by intracerebroventricular injection into mice. Ref.1 Ref.2
Miscellaneous	Has not the same disulfide pairing as other members of alpha-KTx 6.
Sequence similarities	Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 6 subfamily.

Ontologies

Keywords
Cellular component	Secreted
Molecular function	Ionic channel inhibitor Neurotoxin Potassium channel inhibitor Toxin
PTM	Amidation 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 – 34

34

Potassium channel toxin alpha-KTx 6.2

PRO_0000044929

Sites

Site

23

1

Critical for activity

Amino acid modifications

Modified residue

34

1

Cysteine amide

Disulfide bond

3 ↔ 24

Ref.1 Ref.2 Ref.3 Ref.5 Ref.9

Disulfide bond

9 ↔ 29

Ref.1 Ref.2 Ref.3 Ref.5 Ref.9

Disulfide bond

13 ↔ 19

Ref.1 Ref.2 Ref.3 Ref.5 Ref.9

Disulfide bond

31 ↔ 34

Ref.1 Ref.2 Ref.3 Ref.5 Ref.9

Experimental info

Mutagenesis

15

1

K → Q: Induces a change in the third and fourth disulfide bonds, leading to disulfide bonds between C-13 and C-31, and C-19 and C-34. Ref.5

Mutagenesis

23

1

K → A: 1000-fold decrease in affinity. Ref.6

Mutagenesis

33

1

G → A: Induces a change in the third and fourth disulfide bonds, leading to disulfide bonds between C-13 and C-31, and C-19 and C-34. Ref.5

Secondary structure

1

.

.

.

.

.

.

.

34

Helix Strand Turn

Details...

Helix

6 – 17

12

Beta strand

22 – 25

4

Beta strand

28 – 31

4

Sequences

	Sequence		Length	Mass (Da)
	P80719-1 [UniParc]. Last modified November 1, 1997. Version 1. Checksum: FB0BE07370536A48	FASTA	34	3,621
	10 20 30 VSCTGSKDCY APCRKQTGCP NAKCINKSCK CYGC

References

[1]	"Chemical synthesis and characterization of maurotoxin, a short scorpion toxin with four disulfide bridges that acts on K+ channels." Kharrat R., Mabrouk K., Crest M., Darbon H., Oughideni R., Martin-Eauclaire M.-F., Jacquet G., el Ayeb M., van Rietschoten J., Rochat H., Sabatier J.-M. Eur. J. Biochem. 242:491-498(1996) [PubMed: 9022673] [Abstract] Cited for: PROTEIN SEQUENCE, FUNCTION, SYNTHESIS, DISULFIDE BONDS, LETHAL DOSE.
[2]	"Maurotoxin, a four disulfide bridge toxin from Scorpio maurus venom: purification, structure and action on potassium channels." Kharrat R., Mansuelle P., Sampieri F., Crest M., Oughideni R., Van Rietschoten J., Martin-Eauclaire M.-F., Rochat H., El Ayeb M. FEBS Lett. 406:284-290(1997) [PubMed: 9136903] [Abstract] Cited for: PROTEIN SEQUENCE, FUNCTION, SYNTHESIS, DISULFIDE BONDS, LETHAL DOSE. Tissue: Venom.
[3]	"Maurotoxin, a four disulfide bridges scorpion toxin acting on K+ channels." Rochat H., Kharrat R., Sabatier J.-M., Mansuelle P., Crest M., Martin-Eauclaire M.-F., Sampieri F., Oughideni R., Mabrouk K., Jacquet G., Van Rietschoten J., El Ayeb M. Toxicon 36:1609-1611(1998) [PubMed: 9792177] [Abstract] Cited for: SYNTHESIS, AMIDATION AT CYS-34, DISULFIDE BONDS.
[4]	"Mechanisms of maurotoxin action on Shaker potassium channels." Avdonin V., Nolan B., Sabatier J.-M., De Waard M., Hoshi T. Biophys. J. 79:776-787(2000) [PubMed: 10920011] [Abstract] Cited for: FUNCTION.
[5]	"Maurotoxin versus Pi1/HsTx1 scorpion toxins. Toward new insights in the understanding of their distinct disulfide bridge patterns." Fajloun Z., Mosbah A., Carlier E., Mansuelle P., Sandoz G., Fathallah M., di Luccio E., Devaux C., Rochat H., Darbon H., De Waard M., Sabatier J.-M. J. Biol. Chem. 275:39394-39402(2000) [PubMed: 10970898] [Abstract] Cited for: DISULFIDE BONDS, MUTAGENESIS OF LYS-15 AND GLY-33.
[6]	"Effect of maurotoxin, a four disulfide-bridged toxin from the chactoid scorpion Scorpio maurus, on Shaker K+ channels." Carlier E., Avdonin V., Geib S., Fajloun Z., Kharrat R., Rochat H., Sabatier J.-M., Hoshi T., De Waard M. J. Pept. Res. 55:419-427(2000) [PubMed: 10888198] [Abstract] Cited for: MUTAGENESIS OF LYS-23.
[7]	"Maurotoxin: a potent inhibitor of intermediate conductance Ca2+-activated potassium channels." Castle N.A., London D.O., Creech C., Fajloun Z., Stocker J.W., Sabatier J.-M. Mol. Pharmacol. 63:409-418(2003) [PubMed: 12527813] [Abstract] Cited for: FUNCTION.
[8]	"Evidence for domain-specific recognition of SK and Kv channels by MTX and HsTx1 scorpion toxins." Regaya I., Beeton C., Ferrat G., Andreotti N., Darbon H., De Waard M., Sabatier J.M. J. Biol. Chem. 279:55690-55696(2004) [PubMed: 15498765] [Abstract] Cited for: FUNCTION, STRUCTURE BY NMR OF MAUROTOXIN-HSTX1 CHIMERA.
[9]	"Solution structure of maurotoxin, a scorpion toxin from Scorpio maurus, with high affinity for voltage-gated potassium channels." Blanc E., Sabatier J.-M., Kharrat R., Meunier S., el Ayeb M., van Rietschoten J., Darbon H. Proteins 29:321-333(1997) [PubMed: 9365987] [Abstract] Cited for: STRUCTURE BY NMR, DISULFIDE BONDS.
[10]	"Structural and functional consequences of the presence of a fourth disulfide bridge in the scorpion short toxins: solution structure of the potassium channel inhibitor HsTX1." Savarin P., Romi-Lebrun R., Zinn-Justin S., Lebrun B., Nakajima T., Gilquin B., Menez A. Protein Sci. 8:2672-2685(1999) [PubMed: 10631983] [Abstract] Cited for: STRUCTURE BY NMR.
[11]	"Increasing the molecular contacts between maurotoxin and Kv1.2 channel augments ligand affinity." M'Barek S., Chagot B., Andreotti N., Visan V., Mansuelle P., Grissmer S., Marrakchi M., El Ayeb M., Sampieri F., Darbon H., Fajloun Z., De Waard M., Sabatier J.-M. Proteins 60:401-411(2005) [PubMed: 15971207] [Abstract] Cited for: STRUCTURE BY NMR OF MAUROTOXIN-BUTANTOXIN CHIMERA.

Cross-references

3D structure databases

PDBPDBe

Entry	Method	Resolution (Å)	Chain	Positions	PDBsum
1TXM	NMR	-	A	1-34	[»]
1WPD	NMR	-	A	1-31	[»]
1WT7	NMR	-	A	4-34	[»]

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

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Entry information

Entry name

KAX62_SCOMA

Accession

Primary (citable) accession number: P80719

Entry history

Integrated into UniProtKB/Swiss-Prot:	November 1, 1997
Last sequence update:	November 1, 1997
Last modified:	November 3, 2009
This is version 73 of the entry and version 1 of the sequence. [Complete history]

Entry status

Reviewed (UniProtKB/Swiss-Prot)

Annotation project

Tox-Prot (Toxin Annotation Project)