ID   3SDC3_OPHHA             Reviewed;          84 AA.
AC   Q2VBN4;
DT   15-JAN-2008, integrated into UniProtKB/Swiss-Prot.
DT   10-JAN-2006, sequence version 1.
DT   25-MAY-2022, entry version 62.
DE   RecName: Full=Beta-cardiotoxin CTX23;
DE   Flags: Precursor;
OS   Ophiophagus hannah (King cobra) (Naja hannah).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Elapinae; Ophiophagus.
OX   NCBI_TaxID=8665;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Venom gland;
RX   PubMed=16689684; DOI=10.1042/bj20060004;
RA   Li J., Zhang H., Liu J., Xu K.;
RT   "Novel genes encoding six kinds of three-finger toxins in Ophiophagus
RT   hannah (king cobra) and function characterization of two recombinant long-
RT   chain neurotoxins.";
RL   Biochem. J. 398:233-242(2006).
RN   [2]
RP   IDENTIFICATION BY MASS SPECTROMETRY.
RC   TISSUE=Venom;
RX   PubMed=24297900; DOI=10.1073/pnas.1314702110;
RA   Vonk F.J., Casewell N.R., Henkel C.V., Heimberg A.M., Jansen H.J.,
RA   McCleary R.J., Kerkkamp H.M., Vos R.A., Guerreiro I., Calvete J.J.,
RA   Wuster W., Woods A.E., Logan J.M., Harrison R.A., Castoe T.A.,
RA   de Koning A.P., Pollock D.D., Yandell M., Calderon D., Renjifo C.,
RA   Currier R.B., Salgado D., Pla D., Sanz L., Hyder A.S., Ribeiro J.M.,
RA   Arntzen J.W., van den Thillart G.E., Boetzer M., Pirovano W., Dirks R.P.,
RA   Spaink H.P., Duboule D., McGlinn E., Kini R.M., Richardson M.K.;
RT   "The king cobra genome reveals dynamic gene evolution and adaptation in the
RT   snake venom system.";
RL   Proc. Natl. Acad. Sci. U.S.A. 110:20651-20656(2013).
CC   -!- FUNCTION: Acts as a beta-blocker by binding to beta-1 and beta-2
CC       adrenergic receptors (ADRB1 and ADRB2). It dose-dependently decreases
CC       the heart rate (bradycardia), whereas conventional cardiotoxins
CC       increases it. At 100 mg/kg, intraperitoneal injection into mice
CC       provokes labored breathing, impaired locomotion, lack of response to
CC       external stimuli, and death (after 30 min).
CC       {ECO:0000250|UniProtKB:Q69CK0}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000305|PubMed:24297900}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- MISCELLANEOUS: Does not affect blood coagulation and does not show
CC       significant hemolytic activity. {ECO:0000250|UniProtKB:Q69CK0}.
CC   -!- MISCELLANEOUS: Is classified as a P-type cytotoxin, since a proline
CC       residue stands at position 52 (Pro-31 in standard classification).
CC       {ECO:0000305}.
CC   -!- SIMILARITY: Belongs to the snake three-finger toxin family. Short-chain
CC       subfamily. Aminergic toxin sub-subfamily. {ECO:0000305}.
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DR   EMBL; DQ273581; ABB83635.1; -; mRNA.
DR   AlphaFoldDB; Q2VBN4; -.
DR   SMR; Q2VBN4; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   CDD; cd00206; snake_toxin; 1.
DR   Gene3D; 2.10.60.10; -; 1.
DR   InterPro; IPR003572; Cytotoxin_Cobra.
DR   InterPro; IPR016054; LY6_UPA_recep-like.
DR   InterPro; IPR003571; Snake_3FTx.
DR   InterPro; IPR045860; Snake_toxin-like_sf.
DR   InterPro; IPR018354; Snake_toxin_con_site.
DR   Pfam; PF00021; UPAR_LY6; 1.
DR   PRINTS; PR00282; CYTOTOXIN.
DR   SUPFAM; SSF57302; SSF57302; 1.
DR   PROSITE; PS00272; SNAKE_TOXIN; 1.
PE   1: Evidence at protein level;
KW   Cardiotoxin; Disulfide bond; G-protein coupled receptor impairing toxin;
KW   Secreted; Signal; Toxin.
FT   SIGNAL          1..21
FT                   /evidence="ECO:0000250|UniProtKB:Q69CK0"
FT   CHAIN           22..84
FT                   /note="Beta-cardiotoxin CTX23"
FT                   /id="PRO_5000006491"
FT   DISULFID        24..43
FT                   /evidence="ECO:0000250|UniProtKB:Q69CK0"
FT   DISULFID        36..61
FT                   /evidence="ECO:0000250|UniProtKB:Q69CK0"
FT   DISULFID        65..76
FT                   /evidence="ECO:0000250|UniProtKB:Q69CK0"
FT   DISULFID        77..82
FT                   /evidence="ECO:0000250|UniProtKB:Q69CK0"
SQ   SEQUENCE   84 AA;  9296 MW;  9371F5E7A07CB55F CRC64;
     MKTLLLTLVV VTIVCLDLGY TRKCLNTPLP LIYKTCPIGQ DKCIKMTIKK LPSKYDVIRG
     CTDICPKSSA DVVVVCCDTN KCNK