ID   3SL8_DENJA              Reviewed;          60 AA.
AC   P25683;
DT   01-MAY-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1992, sequence version 1.
DT   25-MAY-2022, entry version 82.
DE   RecName: Full=Toxin S4C8;
OS   Dendroaspis jamesoni kaimosae (Eastern Jameson's mamba).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Elapidae; Elapinae; Dendroaspis.
OX   NCBI_TaxID=8619;
RN   [1]
RP   PROTEIN SEQUENCE, TOXIC DOSE, AND SUBCELLULAR LOCATION.
RC   TISSUE=Venom;
RX   PubMed=7428994; DOI=10.1016/0020-711x(80)90008-7;
RA   Joubert F.J., Taljaard N.;
RT   "The primary structure of a short neurotoxin homologue (S4C8) from
RT   Dendroaspis jamesoni kaimosae (Jameson's mamba) venom.";
RL   Int. J. Biochem. 12:567-574(1980).
CC   -!- FUNCTION: This specific blocker of the L-type calcium channel
CC       (Cav1/CACNA1) is a smooth muscle relaxant and an inhibitor of cardiac
CC       contractions. {ECO:0000250|UniProtKB:P01414}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:7428994}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland. {ECO:0000305}.
CC   -!- TOXIC DOSE: LD(50) is 13.7 mg/kg by intravenous injection.
CC       {ECO:0000269|PubMed:7428994}.
CC   -!- SIMILARITY: Belongs to the snake three-finger toxin family. Short-chain
CC       subfamily. L-type calcium blocker sub-subfamily. {ECO:0000305}.
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DR   AlphaFoldDB; P25683; -.
DR   SMR; P25683; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0005246; F:calcium channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   Gene3D; 2.10.60.10; -; 1.
DR   InterPro; IPR045860; Snake_toxin-like_sf.
DR   InterPro; IPR018354; Snake_toxin_con_site.
DR   SUPFAM; SSF57302; SSF57302; 1.
DR   PROSITE; PS00272; SNAKE_TOXIN; 1.
PE   1: Evidence at protein level;
KW   Calcium channel impairing toxin; Cardiotoxin; Direct protein sequencing;
KW   Disulfide bond; Ion channel impairing toxin; Secreted; Toxin;
KW   Voltage-gated calcium channel impairing toxin.
FT   CHAIN           1..60
FT                   /note="Toxin S4C8"
FT                   /evidence="ECO:0000269|PubMed:7428994"
FT                   /id="PRO_0000093663"
FT   REGION          41..48
FT                   /note="Important for binding to L-type calcium channels"
FT                   /evidence="ECO:0000250|UniProtKB:P01414"
FT   DISULFID        3..22
FT                   /evidence="ECO:0000250|UniProtKB:P0C1Z0"
FT   DISULFID        17..39
FT                   /evidence="ECO:0000250|UniProtKB:P0C1Z0"
FT   DISULFID        41..52
FT                   /evidence="ECO:0000250|UniProtKB:P0C1Z0"
FT   DISULFID        53..58
FT                   /evidence="ECO:0000250|UniProtKB:P0C1Z0"
SQ   SEQUENCE   60 AA;  6968 MW;  56F60AAD54F9477E CRC64;
     RICYTHKSLQ AKTTKSCEGN TCYKMFIRTS REYISERGCG CPTAMWPYQT ECCKGDRCNK