ID   TX2B_EUCCO              Reviewed;          29 AA.
AC   P0DQO6;
DT   10-FEB-2021, integrated into UniProtKB/Swiss-Prot.
DT   10-FEB-2021, sequence version 1.
DT   25-MAY-2022, entry version 4.
DE   RecName: Full=Lambda-theraphotoxin-Ec2b {ECO:0000305};
DE            Short=Lambda-TRTX-Ec2b {ECO:0000305};
DE   AltName: Full=Kappa-theraphotoxin-Ec2b {ECO:0000303|PubMed:21447641};
DE            Short=Kappa-TRTX-Ec2b {ECO:0000303|PubMed:21447641};
OS   Eucratoscelus constrictus (African red-rump baboon spider).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida; Araneae;
OC   Mygalomorphae; Theraphosidae; Eucratoscelus.
OX   NCBI_TaxID=2771863;
RN   [1]
RP   PROTEIN SEQUENCE, FUNCTION, SUBCELLULAR LOCATION, MASS SPECTROMETRY, AND
RP   TOXIC DOSE.
RC   TISSUE=Venom;
RX   PubMed=21447641; DOI=10.1124/mol.110.070540;
RA   Windley M.J., Escoubas P., Valenzuela S.M., Nicholson G.M.;
RT   "A novel family of insect-selective peptide neurotoxins targeting insect
RT   large-conductance calcium-activated K+ channels isolated from the venom of
RT   the theraphosid spider Eucratoscelus constrictus.";
RL   Mol. Pharmacol. 80:1-13(2011).
CC   -!- FUNCTION: Insect-selective neurotoxin that potently blocks insect
CC       calcium-activated potassium (BKCa) channels (Slo-type) in cockroach
CC       dorsal unpaired median (DUM) neurons (IC(50)=25.3 nM)
CC       (PubMed:21447641). This occurs in the absence of any shifts in the
CC       voltage dependence of activation (PubMed:21447641). May interact with
CC       the turret and/or loop region of the external entrance to the channel
CC       and does not project deeply into the pore of the channel (Probable). In
CC       vivo, does not show toxicity in mice after intracerebroventricular
CC       injection of up to 25 pmol/g (1.8 ug/20 g mouse) (PubMed:21447641).
CC       {ECO:0000269|PubMed:21447641, ECO:0000305|PubMed:21447641}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:21447641}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000305|PubMed:21447641}.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin.
CC       {ECO:0000250|UniProtKB:P83476}.
CC   -!- MASS SPECTROMETRY: Mass=3676.71; Method=MALDI; Note=Monoisotopic mass.;
CC       Evidence={ECO:0000269|PubMed:21447641};
CC   -!- TOXIC DOSE: Intrathoracical injection into juvenile crickets (Gryllus
CC       bimaculatus) of this toxin (at a dose of ca. 1100 pmol/g (4 ug/g))
CC       causes a rapid insecticidal activity, with complete paralysis within 5
CC       minutes and death within 15 minutes. {ECO:0000269|PubMed:21447641}.
CC   -!- MISCELLANEOUS: At concentrations up to 330 nM, does not show activity
CC       on transient 'A-type' Kv, delayed-rectifier Kv, voltage-gated sodium
CC       channel (Nav) and both HVA and M-LVA Cav channels in cockroach DUM
CC       neurons. {ECO:0000269|PubMed:21447641}.
CC   -!- SIMILARITY: Belongs to the neurotoxin 30 (phrixotoxin) family.
CC       {ECO:0000305}.
CC   -!- CAUTION: This toxin has the prefix lambda in its name (instead of
CC       kappa), since lambda is the Greek letter attributed to calcium-
CC       activated potassium (KCa) channel impairing toxins (according to the
CC       nomenclature of King et al., 2008). {ECO:0000305}.
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DR   AlphaFoldDB; P0DQO6; -.
DR   SMR; P0DQO6; -.
DR   GO; GO:0005576; C:extracellular region; 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.
PE   1: Evidence at protein level;
KW   Calcium-activated potassium channel impairing toxin;
KW   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Neurotoxin; Potassium channel impairing toxin; Secreted; Toxin.
FT   PEPTIDE         1..29
FT                   /note="Lambda-theraphotoxin-Ec2b"
FT                   /id="PRO_0000451987"
FT   DISULFID        2..16
FT                   /evidence="ECO:0000250|UniProtKB:P83476"
FT   DISULFID        9..21
FT                   /evidence="ECO:0000250|UniProtKB:P83476"
FT   DISULFID        15..25
FT                   /evidence="ECO:0000250|UniProtKB:P83476"
SQ   SEQUENCE   29 AA;  3685 MW;  9BC4DA50131B9B28 CRC64;
     YCQKFLWTCD TERKCCEDMV CELWCKYKE