ID   SRTX1_ATRIR             Reviewed;         118 AA.
AC   P0DJK0;
DT   06-FEB-2013, integrated into UniProtKB/Swiss-Prot.
DT   06-FEB-2013, sequence version 1.
DT   25-MAY-2022, entry version 18.
DE   RecName: Full=Sarafotoxin-i1;
DE            Short=SRTX-i1;
DE   AltName: Full=Sarafotoxin-i3;
DE            Short=SRTX-i3;
DE   Flags: Precursor;
OS   Atractaspis irregularis (Variable burrowing asp) (Elaps irregularis).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Lamprophiidae; Atractaspidinae; Atractaspis.
OX   NCBI_TaxID=512568;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], PROTEIN SEQUENCE OF 85-109, MASS SPECTROMETRY,
RP   AND PROBABLE RNA EDITING.
RC   TISSUE=Venom, and Venom gland;
RX   PubMed=16223250; DOI=10.1021/ac050575k;
RA   Quinton L., Le Caer J.P., Phan G., Ligny-Lemaire C., Bourdais-Jomaron J.,
RA   Ducancel F., Chamot-Rooke J.;
RT   "Characterization of toxins within crude venoms by combined use of Fourier
RT   transform mass spectrometry and cloning.";
RL   Anal. Chem. 77:6630-6639(2005).
RN   [2]
RP   SYNTHESIS OF 85-109, FUNCTION (SARAFOTOXIN-I3), STRUCTURE BY NMR OF 85-109,
RP   DISULFIDE BONDS, AND MUTAGENESIS OF 106-ILE--ASN-109.
RX   PubMed=21889567; DOI=10.1016/j.biochi.2011.08.014;
RA   Mourier G., Hajj M., Cordier F., Zorba A., Gao X., Coskun T., Herbet A.,
RA   Marcon E., Beau F., Delepierre M., Ducancel F., Servent D.;
RT   "Pharmacological and structural characterization of long-sarafotoxins, a
RT   new family of endothelin-like peptides: role of the C-terminus extension.";
RL   Biochimie 94:461-470(2012).
CC   -!- FUNCTION: Vasoconstrictor activity. These toxins cause cardiac arrest
CC       probably as a result of coronary vasospasm (By similarity).
CC       {ECO:0000250}.
CC   -!- FUNCTION: Sarafotoxin-i3: vasoconstrictor activity. Causes cardiac
CC       arrest probably as a result of coronary vasospasm (By similarity).
CC       Displays low agonistic activities towards endothelin-2 receptor (EDNRB)
CC       (displays affinity in the micromolar range). {ECO:0000250,
CC       ECO:0000269|PubMed:21889567}.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC   -!- PTM: Different length molecules ranging from 15 (85-99) to 30 amino
CC       acids (85-114) have been found in the venom.
CC       {ECO:0000269|PubMed:16223250}.
CC   -!- RNA EDITING: Modified_positions=106 {ECO:0000305}; Note=RNA editing may
CC       explain why no precursor for this sequence have been cloned.
CC       {ECO:0000305};
CC   -!- MASS SPECTROMETRY: Mass=2972.2; Method=Electrospray; Note=Monoisotopic
CC       mass, sarafotoxin-i1.; Evidence={ECO:0000269|PubMed:16223250};
CC   -!- MASS SPECTROMETRY: Mass=2958.2; Method=Electrospray; Note=Monoisotopic
CC       mass, sarafotoxin-i3.; Evidence={ECO:0000269|PubMed:16223250};
CC   -!- SIMILARITY: Belongs to the endothelin/sarafotoxin family.
CC       {ECO:0000305}.
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DR   PDB; 2LDE; NMR; -; A=85-109.
DR   PDBsum; 2LDE; -.
DR   AlphaFoldDB; P0DJK0; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   GO; GO:0019229; P:regulation of vasoconstriction; IEA:InterPro.
DR   GO; GO:0042310; P:vasoconstriction; IEA:UniProtKB-KW.
DR   InterPro; IPR019764; Endothelin_toxin_CS.
DR   InterPro; IPR001928; Endothln-like_toxin.
DR   Pfam; PF00322; Endothelin; 1.
DR   SMART; SM00272; END; 1.
DR   PROSITE; PS00270; ENDOTHELIN; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Cardiotoxin; Cleavage on pair of basic residues;
KW   Direct protein sequencing; Disulfide bond;
KW   G-protein coupled receptor impairing toxin; RNA editing; Secreted; Signal;
KW   Toxin; Vasoactive; Vasoconstrictor.
FT   SIGNAL          1..23
FT                   /evidence="ECO:0000255"
FT   PROPEP          24..84
FT                   /evidence="ECO:0000269|PubMed:16223250"
FT                   /id="PRO_0000421164"
FT   PEPTIDE         85..109
FT                   /note="Sarafotoxin-i1"
FT                   /id="PRO_0000421165"
FT   PROPEP          112..118
FT                   /id="PRO_0000421166"
FT   SITE            105
FT                   /note="Endothelin-receptor binding site"
FT                   /evidence="ECO:0000250"
FT   DISULFID        85..99
FT                   /evidence="ECO:0000250"
FT   DISULFID        87..95
FT                   /evidence="ECO:0000250"
FT   VARIANT         106
FT                   /note="I -> V (in RNA edited version, Sarafotoxin-i3)"
FT   MUTAGEN         106..109
FT                   /note="Missing: Drastic 4-orders or magnitude increase in
FT                   affinity for ET-B receptors."
FT                   /evidence="ECO:0000269|PubMed:21889567"
SQ   SEQUENCE   118 AA;  12722 MW;  D16BD000685310C1 CRC64;
     MALLPRLAAG GLLLLLALAA LDGKPAPPKL LQKLMDGGQR RSEDQAAAGR IIDYEDGDEP
     VAVSVGDTKQ AARALSPLRK PQPLCSCTDM SDLECMNFCH KDVIWINRNR KPSPIQSS