KAX24_CENNO
ID KAX24_CENNO Reviewed; 38 AA.
AC Q9TXD1;
DT 26-SEP-2003, integrated into UniProtKB/Swiss-Prot.
DT 01-MAY-2000, sequence version 1.
DT 25-MAY-2022, entry version 70.
DE RecName: Full=Potassium channel toxin alpha-KTx 2.4;
DE AltName: Full=Noxiustoxin-2 {ECO:0000303|PubMed:8875778};
DE Short=NTx2 {ECO:0000303|PubMed:8875778};
OS Centruroides noxius (Mexican scorpion).
OC Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Arachnida;
OC Scorpiones; Buthida; Buthoidea; Buthidae; Centruroides.
OX NCBI_TaxID=6878;
RN [1]
RP PROTEIN SEQUENCE, FUNCTION, AND SUBCELLULAR LOCATION.
RC TISSUE=Venom;
RX PubMed=8875778; DOI=10.1016/0041-0101(96)00029-3;
RA Nieto A.R., Gurrola G.B., Vaca L., Possani L.D.;
RT "Noxiustoxin 2, a novel K+ channel blocking peptide from the venom of the
RT scorpion Centruroides noxius Hoffmann.";
RL Toxicon 34:913-922(1996).
CC -!- FUNCTION: Blocks voltage-gated non-inactivating potassium channels (Kv)
CC and unblocks inactivating potassium channels blocked by alpha-
CC dendrotoxin in synaptosomes. It is not toxic to mice and crustaceans,
CC but has a paralysing effect on crickets. {ECO:0000269|PubMed:8875778}.
CC -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:8875778}.
CC -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC {ECO:0000305|PubMed:8875778}.
CC -!- DOMAIN: Has the structural arrangement of an alpha-helix connected to a
CC beta-sheet by disulfide bonds (CSalpha/beta).
CC {ECO:0000250|UniProtKB:P08815}.
CC -!- DOMAIN: The N-terminus is probably essential for channel affinity.
CC {ECO:0000305|PubMed:8875778}.
CC -!- MISCELLANEOUS: NTX2 has a thousandfold less affinity than NTX, for the
CC potassium channels (Kv) of synaptosomes. In addition, it shows a lower
CC potency (over two logarithm units) than noxiustoxin (AC P08815) in
CC producing 50% blockade of the probability of opening small conductance
CC calcium-activated potassium (KCa) (obtained from cultured bovine aortic
CC endothelial cells). {ECO:0000269|PubMed:8875778}.
CC -!- SIMILARITY: Belongs to the short scorpion toxin superfamily. Potassium
CC channel inhibitor family. Alpha-KTx 02 subfamily. {ECO:0000305}.
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DR AlphaFoldDB; Q9TXD1; -.
DR SMR; Q9TXD1; -.
DR GO; GO:0005576; C:extracellular region; 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:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR Gene3D; 3.30.30.10; -; 1.
DR InterPro; IPR036574; Scorpion_toxin-like_sf.
DR InterPro; IPR001947; Scorpion_toxinS_K_inh.
DR Pfam; PF00451; Toxin_2; 1.
DR PRINTS; PR00286; CHARYBDTOXIN.
DR SUPFAM; SSF57095; SSF57095; 1.
DR PROSITE; PS01138; SCORP_SHORT_TOXIN; 1.
PE 1: Evidence at protein level;
KW Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW Neurotoxin; Potassium channel impairing toxin; Secreted; Toxin;
KW Voltage-gated potassium channel impairing toxin.
FT PEPTIDE 1..38
FT /note="Potassium channel toxin alpha-KTx 2.4"
FT /evidence="ECO:0000269|PubMed:8875778"
FT /id="PRO_0000044906"
FT SITE 27
FT /note="Basic residue of the functional dyad"
FT /evidence="ECO:0000250"
FT SITE 36
FT /note="Aromatic residue of the functional dyad"
FT /evidence="ECO:0000250"
FT DISULFID 7..28
FT /evidence="ECO:0000250|UniProtKB:P08815"
FT DISULFID 13..33
FT /evidence="ECO:0000250|UniProtKB:P08815"
FT DISULFID 17..35
FT /evidence="ECO:0000250|UniProtKB:P08815"
SQ SEQUENCE 38 AA; 4189 MW; 64E3A9BA12C8B8BA CRC64;
TIINEKCFAT SQCWTPCKKA IGSLQSKCMN GKCKCYNG
