K1B2_BUNCI
ID K1B2_BUNCI Reviewed; 37 AA.
AC C0HJC3;
DT 24-JUL-2013, integrated into UniProtKB/Swiss-Prot.
DT 24-JUL-2013, sequence version 1.
DT 25-MAY-2022, entry version 18.
DE RecName: Full=Kappa-actitoxin-Bcs3b {ECO:0000305};
DE Short=Kappa-AITX-Bcs3b {ECO:0000305};
DE AltName: Full=Potassium channel toxin BcsTx2 {ECO:0000303|PubMed:23466933};
DE Short=BcsTx2 {ECO:0000303|PubMed:23466933};
OS Bunodosoma caissarum (Sea anemone).
OC Eukaryota; Metazoa; Cnidaria; Anthozoa; Hexacorallia; Actiniaria;
OC Actiniidae; Bunodosoma.
OX NCBI_TaxID=31165;
RN [1]
RP PROTEIN SEQUENCE, FUNCTION, SUBCELLULAR LOCATION, AND MASS SPECTROMETRY.
RX PubMed=23466933; DOI=10.3390/md11030655;
RA Orts D.J., Peigneur S., Madio B., Cassoli J.S., Montandon G.G.,
RA Pimenta A.M., Bicudo J.E., Freitas J.C., Zaharenko A.J., Tytgat J.;
RT "Biochemical and electrophysiological characterization of two sea anemone
RT type 1 potassium toxins from a geographically distant population of
RT Bunodosoma caissarum.";
RL Mar. Drugs 11:655-679(2013).
CC -!- FUNCTION: Inhibits voltage-gated potassium channels (IC(50)=14.42 nM
CC for rKCNA1/Kv1.1, IC(50)=80.4 nM for rKCNA2/Kv1.2, IC(50)=7.76 nM for
CC rKCNA6/Kv1.6, IC(50)=13.12 nM for hKCNA3/Kv1.3, and IC(50)=49.14 nM for
CC insect Shaker IR). Binds the Shaker IR channels in a voltage-
CC independent manner. {ECO:0000269|PubMed:23466933}.
CC -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:23466933}.
CC Nematocyst {ECO:0000269|PubMed:23466933}.
CC -!- MASS SPECTROMETRY: Mass=3914.52; Method=MALDI;
CC Evidence={ECO:0000269|PubMed:23466933};
CC -!- MISCELLANEOUS: No cytolytic activity on erythrocytes detected. Not
CC active on rat KCNA4/Kv1.4 or KCNA5/Kv1.5 channels.
CC {ECO:0000269|PubMed:23466933}.
CC -!- SIMILARITY: Belongs to the sea anemone type 1 potassium channel toxin
CC family. Type 1b subfamily. {ECO:0000305}.
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DR AlphaFoldDB; C0HJC3; -.
DR SMR; C0HJC3; -.
DR GO; GO:0005576; C:extracellular region; IDA:UniProtKB.
DR GO; GO:0042151; C:nematocyst; NAS:UniProtKB.
DR GO; GO:0019870; F:potassium channel inhibitor activity; IDA:UniProtKB.
DR GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR GO; GO:0044361; P:negative regulation of voltage-gated potassium channel activity in another organism; IDA:UniProtKB.
DR InterPro; IPR003582; ShKT_dom.
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..37
FT /note="Kappa-actitoxin-Bcs3b"
FT /evidence="ECO:0000269|PubMed:23466933"
FT /id="PRO_0000423184"
FT DOMAIN 2..37
FT /note="ShKT"
FT /evidence="ECO:0000255|PROSITE-ProRule:PRU01005"
FT REGION 25..26
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|UniProtKB:P29186"
FT SITE 13
FT /note="Important for binding to potassium channels"
FT /evidence="ECO:0000250|UniProtKB:P29186"
FT SITE 23
FT /note="Important for binding to potassium channels"
FT /evidence="ECO:0000250|UniProtKB:P29186"
FT DISULFID 2..37
FT /evidence="ECO:0000250|UniProtKB:P29186,
FT ECO:0000255|PROSITE-ProRule:PRU01005"
FT DISULFID 11..30
FT /evidence="ECO:0000250|UniProtKB:P29186,
FT ECO:0000255|PROSITE-ProRule:PRU01005"
FT DISULFID 20..34
FT /evidence="ECO:0000250|UniProtKB:P29186,
FT ECO:0000255|PROSITE-ProRule:PRU01005"
SQ SEQUENCE 37 AA; 3919 MW; 6D362B6C223039E3 CRC64;
ACKDGFPTAT CQHAKLVGNC KNSQKYRANC AKTCGPC
