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UniProtKB - P59867 (KAX63_HETSP)
Protein
Potassium channel toxin alpha-KTx 6.3
Gene
N/A
Organism
Heterometrus spinifer (Asia giant forest scorpion) (Malaysian black scorpion)
Status
Functioni
Potently blocks voltage-gated potassium channels Kv1.1/KCNA1 (IC50=7-11 nM) and Kv1.3/KCNA3 (IC50=11-29 pM) (PubMed:9359871, PubMed:24676092, PubMed:15498765).
Also mildly blocks intermediate (IK) conductance calcium-activated potassium channels (KCa3.1/KCNN4) and ERG1/Kv11.1/KCNH2 (PubMed:18687312, PubMed:15498765).
Shows ability to suppress proliferation of lymphocytes, which are known to be sensitive to Kv1.3/KCNA3 homotetrameric channel block (PubMed:24676092).
4 PublicationsMiscellaneous
Does not block Kv1.2/KCNA2 potassium channels (PubMed:15498765). Does not induce hemolysis (PubMed:24676092).2 Publications
PEGylation of HsTX1[R14A] enhances its circulating half-life in rats, reduces its affinity but not its selectivity for Kv1.3/KCNA3, and dramatically reduces its adsorption to inert surfaces. PEG-HsTX1[R14A] is equipotent to HsTX1[R14A] in preferential inhibition of human and rat CCR7- effector memory T lymphocytes (TEM) proliferation, leaving CCR7+ naive and central memory T cells able to proliferate. It reduces inflammation in an active delayed-type hypersensitivity model and in the pristane-induced arthritis (PIA) model of rheumatoid arthritis (RA). Importantly, a single subcutaneous dose of PEG-HsTX1[R14A] reduces inflammation in PIA for a longer period of time than the non-PEGylated HsTX1[R14A]. Together, these data indicate that HsTX1[R14A] and PEG-HsTX1[R14A] are effective in a model of RA and are therefore potential therapeutics for TEM cell-mediated autoimmune diseases.1 Publication
Sites
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Sitei | 21 | Important for activity1 Publication | 1 | |
Sitei | 23 | Critical for activity (is inserted in the pore, pointing downward)1 Publication | 1 | |
Sitei | 25 | Important for activity1 Publication | 1 | |
Sitei | 26 | Important for activity1 Publication | 1 | |
Sitei | 33 | Important for activity1 Publication | 1 |
GO - Molecular functioni
- ion channel inhibitor activity Source: InterPro
- potassium channel regulator activity Source: UniProtKB-KW
- toxin activity Source: UniProtKB-KW
Keywordsi
Names & Taxonomyi
Protein namesi | Recommended name: Potassium channel toxin alpha-KTx 6.3Alternative name(s): Neurotoxin HsTX11 Publication |
Organismi | Heterometrus spinifer (Asia giant forest scorpion) (Malaysian black scorpion) |
Taxonomic identifieri | 118530 [NCBI] |
Taxonomic lineagei | Eukaryota › Metazoa › Ecdysozoa › Arthropoda › Chelicerata › Arachnida › Scorpiones › Iurida › Scorpionoidea › Scorpionidae › Heterometrinae › Heterometrus |
Subcellular locationi
Extracellular region or secreted
- Secreted 1 Publication
Extracellular region or secreted
- extracellular region Source: UniProtKB-SubCell
Keywords - Cellular componenti
SecretedPathology & Biotechi
Pharmaceutical usei
Some analogs of this peptide are potential candidate for treatment of autoimmune diseases through block of Kv1.3/KCNA3.2 Publications
Mutagenesis
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Mutagenesisi | 14 | R → A: Increase in selectivity for Kv1.3/KCNA3 over Kv1.1/KCNA1 (>2000-fold more selective). Very weak decrease in inhibition of Kv1.3/KCNA3 and important decrease in inhibition of Kv1.1/KCNA1. No change in ability to suppress lymphocyte proliferation. 2 Publications | 1 |
PTM / Processingi
Molecule processing
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
PeptideiPRO_0000044908 | 1 – 34 | Potassium channel toxin alpha-KTx 6.31 PublicationAdd BLAST | 34 |
Amino acid modifications
Feature key | Position(s) | DescriptionActions | Graphical view | Length |
---|---|---|---|---|
Disulfide bondi | 3 ↔ 24 | Combined sources3 PublicationsImported | ||
Disulfide bondi | 9 ↔ 29 | Combined sources3 PublicationsImported | ||
Disulfide bondi | 13 ↔ 31 | Combined sources3 PublicationsImported | ||
Disulfide bondi | 19 ↔ 34 | Combined sources3 Publications | ||
Modified residuei | 34 | Cysteine amide1 Publication | 1 |
Post-translational modificationi
Amidated (PubMed:9359871). The amidated toxin shows 5-fold more affinity for Kv1.3/KCNA3 than the synthetic carboxylated form (PubMed:9359871).1 Publication
Keywords - PTMi
Amidation, Disulfide bondExpressioni
Tissue specificityi
Expressed by the venom gland.1 Publication
Structurei
Secondary structure
Legend: HelixTurnBeta strandPDB Structure known for this area
Show more details3D structure databases
AlphaFoldDBi | P59867 |
BMRBi | P59867 |
SMRi | P59867 |
ModBasei | Search... |
PDBe-KBi | Search... |
Miscellaneous databases
EvolutionaryTracei | P59867 |
Family & Domainsi
Domaini
Has the structural arrangement of an alpha-helix connected to a beta-sheet by disulfide bonds (CSalpha/beta).2 Publications
The lower affinity for Kv1.1/KCNA1 is due to HsTX1 inability to come close to the pore domain, which prevents the pore-inserting lysine (Lys-23) from making proper contacts with the tyrosine carbonyls in the selectivity filter of the channel.1 Publication
Sequence similaritiesi
Belongs to the short scorpion toxin superfamily. Potassium channel inhibitor family. Alpha-KTx 06 subfamily.Curated
Family and domain databases
Gene3Di | 3.30.30.10, 1 hit |
InterProi | View protein in InterPro IPR036574, Scorpion_toxin-like_sf IPR001947, Scorpion_toxinS_K_inh |
Pfami | View protein in Pfam PF00451, Toxin_2, 1 hit |
PRINTSi | PR00286, CHARYBDTOXIN |
SUPFAMi | SSF57095, SSF57095, 1 hit |
PROSITEi | View protein in PROSITE PS01138, SCORP_SHORT_TOXIN, 1 hit |
i Sequence
Sequence statusi: Complete.
Mass spectrometryi
Molecular mass is 3815.63 Da. Determined by MALDI. 1 Publication
Similar proteinsi
Cross-referencesi
3D structure databases
Select the link destinations: PDBei RCSB PDBi PDBji Links Updated | PDB entry | Method | Resolution (Å) | Chain | Positions | PDBsum |
1QUZ | NMR | - | A | 1-34 | [»] | |
1WPD | NMR | - | A | 7-34 | [»] | |
1Y2P | NMR | - | A | 1-34 | [»] | |
AlphaFoldDBi | P59867 | |||||
BMRBi | P59867 | |||||
SMRi | P59867 | |||||
ModBasei | Search... | |||||
PDBe-KBi | Search... |
Miscellaneous databases
EvolutionaryTracei | P59867 |
Family and domain databases
Gene3Di | 3.30.30.10, 1 hit |
InterProi | View protein in InterPro IPR036574, Scorpion_toxin-like_sf IPR001947, Scorpion_toxinS_K_inh |
Pfami | View protein in Pfam PF00451, Toxin_2, 1 hit |
PRINTSi | PR00286, CHARYBDTOXIN |
SUPFAMi | SSF57095, SSF57095, 1 hit |
PROSITEi | View protein in PROSITE PS01138, SCORP_SHORT_TOXIN, 1 hit |
MobiDBi | Search... |
Entry informationi
Entry namei | KAX63_HETSP | |
Accessioni | P59867Primary (citable) accession number: P59867 | |
Entry historyi | Integrated into UniProtKB/Swiss-Prot: | September 26, 2003 |
Last sequence update: | September 26, 2003 | |
Last modified: | May 25, 2022 | |
This is version 84 of the entry and version 1 of the sequence. See complete history. | ||
Entry statusi | Reviewed (UniProtKB/Swiss-Prot) | |
Annotation program | Animal Toxin Annotation Program |
Miscellaneousi
Keywords - Technical termi
3D-structure, Direct protein sequencing, PharmaceuticalDocuments
- Scorpion potassium channel toxins
Nomenclature of scorpion potassium channel toxins and list of entries - PDB cross-references
Index of Protein Data Bank (PDB) cross-references - SIMILARITY comments
Index of protein domains and families