ID   BDS4_ANTEL              Reviewed;          42 AA.
AC   C0HL40;
DT   22-NOV-2017, integrated into UniProtKB/Swiss-Prot.
DT   22-NOV-2017, sequence version 1.
DT   25-MAY-2022, entry version 8.
DE   RecName: Full=Kappa-actitoxin-Ael2e {ECO:0000303|PubMed:28902151};
DE            Short=Kappa-AITX-Ael2e {ECO:0000303|PubMed:28902151};
DE   AltName: Full=Toxin APETx4 {ECO:0000303|PubMed:28902151};
OS   Anthopleura elegantissima (Green aggregating anemone) (Actinia
OS   elegantissima).
OC   Eukaryota; Metazoa; Cnidaria; Anthozoa; Hexacorallia; Actiniaria;
OC   Actiniidae; Anthopleura.
OX   NCBI_TaxID=6110;
RN   [1] {ECO:0000305}
RP   PROTEIN SEQUENCE, IDENTIFICATION BY MASS SPECTROMETRY, FUNCTION,
RP   SUBCELLULAR LOCATION, DOMAIN, AND 3D-STRUCTURE MODELING.
RX   PubMed=28902151; DOI=10.3390/md15090287;
RA   Moreels L., Peigneur S., Galan D.T., De Pauw E., Beress L., Waelkens E.,
RA   Pardo L.A., Quinton L., Tytgat J.;
RT   "APETx4, a novel Sea Anemone toxin and a modulator of the cancer-relevant
RT   potassium channel KV10.1.";
RL   Mar. Drugs 15:287-287(2017).
CC   -!- FUNCTION: Inhibits voltage-gated potassium and sodium channels. It
CC       potently inhibits human Kv10.1/KCNH1/EAG1 (IC(50)=1.1 uM) and
CC       Kv1.4/KCNA4, and moderately inhibits rat Kv1.3/KCNA3, human Kv1.5/KCNA5
CC       and human Kv2.1/KCNB1. Likely to act as a gating-modifier toxin that
CC       binds to closed Kv10.1 channels and reduces their activation by
CC       shifting their voltage-dependence in the positive direction and
CC       suppressing their current amplitudes elicited by strong depolarizing
CC       pulses. On sodium channels, it blocks rat Nav1.4/SCN4A, human
CC       Nav1.5/SCN5A and displays relatively weak inhibition of mouse
CC       Nav1.6/SCN8A. {ECO:0000269|PubMed:28902151}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:28902151}.
CC       Nematocyst {ECO:0000305}.
CC   -!- DOMAIN: Has the CSbeta/beta fold, which comprises anti-parallel beta-
CC       sheets stabilized by three or four disulfide bonds.
CC       {ECO:0000250|UniProtKB:P61541}.
CC   -!- MASS SPECTROMETRY: Mass=4651.02; Method=MALDI;
CC       Evidence={ECO:0000269|PubMed:28902151};
CC   -!- MASS SPECTROMETRY: Mass=4651.00; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:28902151};
CC   -!- MISCELLANEOUS: Does not block human Kv11.1/KCNH2/ERG1, Xenopus laevis
CC       Kv11.1/KCNH2/ERG1 and human Kv1.1/KCNA1. {ECO:0000269|PubMed:28902151}.
CC   -!- SIMILARITY: Belongs to the sea anemone type 3 (BDS) potassium channel
CC       toxin family. {ECO:0000305}.
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DR   AlphaFoldDB; C0HL40; -.
DR   SMR; C0HL40; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0042151; C:nematocyst; IEA:UniProtKB-SubCell.
DR   GO; GO:0008200; F:ion channel inhibitor activity; IEA:InterPro.
DR   GO; GO:0015459; F:potassium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0017080; F:sodium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   Gene3D; 2.20.20.10; -; 1.
DR   InterPro; IPR012414; BDS_K_chnl_tox.
DR   InterPro; IPR023355; Myo_ane_neurotoxin_sf.
DR   Pfam; PF07936; Defensin_4; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Nematocyst; Neurotoxin; Potassium channel impairing toxin; Secreted; Toxin;
KW   Voltage-gated potassium channel impairing toxin;
KW   Voltage-gated sodium channel impairing toxin.
FT   CHAIN           1..42
FT                   /note="Kappa-actitoxin-Ael2e"
FT                   /evidence="ECO:0000269|PubMed:28902151"
FT                   /id="PRO_0000442360"
FT   DISULFID        4..37
FT                   /evidence="ECO:0000250|UniProtKB:P61541"
FT   DISULFID        6..30
FT                   /evidence="ECO:0000250|UniProtKB:P61541"
FT   DISULFID        20..38
FT                   /evidence="ECO:0000250|UniProtKB:P61541"
FT   UNSURE          10
FT                   /note="I or L"
FT                   /evidence="ECO:0000269|PubMed:28902151"
FT   UNSURE          12
FT                   /note="I or L"
FT                   /evidence="ECO:0000269|PubMed:28902151"
FT   UNSURE          34
FT                   /note="L or I"
FT                   /evidence="ECO:0000269|PubMed:28902151"
FT   UNSURE          36
FT                   /note="I or L"
FT                   /evidence="ECO:0000269|PubMed:28902151"
SQ   SEQUENCE   42 AA;  4660 MW;  464E53F50F4B6710 CRC64;
     GTTCYCGKTI GIYWFGKYSC PTNRGYTGSC PYFLGICCYP VD