ID   K1B_ACTEQ               Reviewed;          36 AA.
AC   P81897;
DT   30-MAY-2000, integrated into UniProtKB/Swiss-Prot.
DT   30-MAY-2000, sequence version 1.
DT   25-MAY-2022, entry version 65.
DE   RecName: Full=Kappa-actitoxin-Aeq4a {ECO:0000303|PubMed:22683676};
DE            Short=Kappa-AITX-Aeq4a {ECO:0000303|PubMed:22683676};
DE   AltName: Full=Potassium channel toxin Aek {ECO:0000303|PubMed:9613617};
OS   Actinia equina (Beadlet anemone).
OC   Eukaryota; Metazoa; Cnidaria; Anthozoa; Hexacorallia; Actiniaria;
OC   Actiniidae; Actinia.
OX   NCBI_TaxID=6106;
RN   [1]
RP   PROTEIN SEQUENCE, AND FUNCTION.
RC   TISSUE=Nematoblast;
RX   PubMed=9613617; DOI=10.1016/s0014-5793(98)00403-7;
RA   Minagawa S., Ishida M., Nagashima Y., Shiomi K.;
RT   "Primary structure of a potassium channel toxin from the sea anemone
RT   Actinia equina.";
RL   FEBS Lett. 427:149-151(1998).
RN   [2]
RP   NOMENCLATURE.
RX   PubMed=22683676; DOI=10.1016/j.toxicon.2012.05.020;
RA   Oliveira J.S., Fuentes-Silva D., King G.F.;
RT   "Development of a rational nomenclature for naming peptide and protein
RT   toxins from sea anemones.";
RL   Toxicon 60:539-550(2012).
CC   -!- FUNCTION: Inhibits voltage-dependent potassium channels (Kv1/KCNA).
CC       Inhibits the binding of 125I-alpha-dendrotoxin to rat synaptosomal
CC       membranes (IC(50)=22 nM). {ECO:0000269|PubMed:9613617}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250|UniProtKB:C0HJC2}.
CC       Nematocyst {ECO:0000250|UniProtKB:C0HJC2}.
CC   -!- SIMILARITY: Belongs to the sea anemone type 1 potassium channel toxin
CC       family. Type 1b subfamily. {ECO:0000305}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   AlphaFoldDB; P81897; -.
DR   SMR; P81897; -.
DR   TCDB; 8.B.14.1.3; the sea anemone peptide toxin, class 1 (bgk) family.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0042151; C:nematocyst; IEA:UniProtKB-SubCell.
DR   GO; GO:0015459; F:potassium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   InterPro; IPR003582; ShKT_dom.
DR   Pfam; PF01549; ShK; 1.
DR   PROSITE; PS51670; SHKT; 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.
FT   PEPTIDE         1..36
FT                   /note="Kappa-actitoxin-Aeq4a"
FT                   /evidence="ECO:0000269|PubMed:9613617"
FT                   /id="PRO_0000044863"
FT   DOMAIN          2..36
FT                   /note="ShKT"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01005"
FT   REGION          24..25
FT                   /note="Crucial for binding to potassium channels"
FT                   /evidence="ECO:0000250|UniProtKB:P29186"
FT   SITE            6
FT                   /note="Important for binding to potassium channels"
FT                   /evidence="ECO:0000250"
FT   SITE            13
FT                   /note="Important for binding to potassium channels"
FT                   /evidence="ECO:0000250"
FT   SITE            22
FT                   /note="Important for binding to potassium channels"
FT                   /evidence="ECO:0000250"
FT   DISULFID        2..36
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01005"
FT   DISULFID        11..29
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01005"
FT   DISULFID        20..33
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU01005"
SQ   SEQUENCE   36 AA;  3813 MW;  832A2F8A7E486DC3 CRC64;
     GCKDNFSANT CKHVKANNNC GSQKYATNCA KTCGKC