ID   CAS2_CONST              Reviewed;          72 AA.
AC   P28879; Q8I6R6;
DT   01-DEC-1992, integrated into UniProtKB/Swiss-Prot.
DT   05-SEP-2006, sequence version 3.
DT   25-MAY-2022, entry version 92.
DE   RecName: Full=Alpha-conotoxin SII {ECO:0000303|PubMed:1390774, ECO:0000303|PubMed:15707935};
DE   Flags: Precursor;
OS   Conus striatus (Striated cone).
OC   Eukaryota; Metazoa; Spiralia; Lophotrochozoa; Mollusca; Gastropoda;
OC   Caenogastropoda; Neogastropoda; Conoidea; Conidae; Conus; Pionoconus.
OX   NCBI_TaxID=6493;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Venom duct;
RX   PubMed=10573284; DOI=10.1016/s0196-9781(99)00116-3;
RA   Lu B.-S., Yu F., Zhao D., Huang P.-T., Huang C.-F.;
RT   "Conopeptides from Conus striatus and Conus textile by cDNA cloning.";
RL   Peptides 20:1139-1144(1999).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Venom duct;
RX   PubMed=14602116; DOI=10.1016/j.toxicon.2003.08.005;
RA   Wang C.-Z., Jiang H., Ou Z.-L., Chen J.-S., Chi C.-W.;
RT   "cDNA cloning of two A-superfamily conotoxins from Conus striatus.";
RL   Toxicon 42:613-619(2003).
RN   [3]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Venom duct;
RX   PubMed=14701840; DOI=10.1074/jbc.m309654200;
RA   Santos A.D., McIntosh J.M., Hillyard D.R., Cruz L.J., Olivera B.M.;
RT   "The A-superfamily of conotoxins: structural and functional divergence.";
RL   J. Biol. Chem. 279:17596-17606(2004).
RN   [4]
RP   PROTEIN SEQUENCE OF 51-69, SYNTHESIS OF 51-69, AND SUBCELLULAR LOCATION.
RC   TISSUE=Venom;
RX   PubMed=1390774; DOI=10.1021/bi00156a009;
RA   Ramilo C., Zafaralla G.C., Nadasdi L., Hammerland L.G., Yoshikami D.,
RA   Gray W.R., Kristipati R., Ramachandran J., Miljanich G.P., Olivera B.M.,
RA   Cruz L.J.;
RT   "Novel alpha- and omega-conotoxins from Conus striatus venom.";
RL   Biochemistry 31:9919-9926(1992).
RN   [5]
RP   DISULFIDE BONDS, SYNTHESIS OF 51-69, MASS SPECTROMETRY, AND FUNCTION.
RC   TISSUE=Venom;
RX   PubMed=15707935; DOI=10.1016/j.ab.2004.10.001;
RA   Bingham J.-P., Broxton N.M., Livett B.G., Down J.G., Jones A.,
RA   Moczydlowski E.G.;
RT   "Optimizing the connectivity in disulfide-rich peptides: alpha-conotoxin
RT   SII as a case study.";
RL   Anal. Biochem. 338:48-61(2005).
CC   -!- FUNCTION: Alpha-conotoxins act on postsynaptic membranes, they bind to
CC       the nicotinic acetylcholine receptors (nAChR) and thus inhibit them.
CC       Has no effect on the release of catecholamines evoked by nicotine.
CC       {ECO:0000269|PubMed:15707935}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:1390774}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom duct.
CC       {ECO:0000305|PubMed:1390774}.
CC   -!- DOMAIN: The cysteine framework is II (CCC-C-C-C).
CC   -!- MASS SPECTROMETRY: Mass=1790.3; Method=Electrospray;
CC       Evidence={ECO:0000269|PubMed:15707935};
CC   -!- SIMILARITY: Belongs to the conotoxin A superfamily. {ECO:0000305}.
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DR   EMBL; AY157497; AAN77902.1; -; mRNA.
DR   PIR; A44379; A44379.
DR   PDB; 6OTB; NMR; -; A=51-69.
DR   PDB; 6OVJ; NMR; -; A=52-64.
DR   PDBsum; 6OTB; -.
DR   PDBsum; 6OVJ; -.
DR   AlphaFoldDB; P28879; -.
DR   SMR; P28879; -.
DR   ConoServer; 3900; SII precursor.
DR   ConoServer; 9; SII precursor.
DR   ConoServer; 91; SII precursor.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0035792; C:host cell postsynaptic membrane; IEA:UniProtKB-KW.
DR   GO; GO:0030550; F:acetylcholine receptor inhibitor activity; IEA:UniProtKB-KW.
DR   GO; GO:0099106; F:ion channel regulator activity; IEA:UniProtKB-KW.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   InterPro; IPR009958; Conotoxin_a-typ.
DR   InterPro; IPR018072; Conotoxin_a-typ_CS.
DR   Pfam; PF07365; Toxin_8; 1.
DR   PROSITE; PS60014; ALPHA_CONOTOXIN; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Acetylcholine receptor inhibiting toxin;
KW   Direct protein sequencing; Disulfide bond; Ion channel impairing toxin;
KW   Neurotoxin; Postsynaptic neurotoxin; Secreted; Signal; Toxin.
FT   SIGNAL          1..21
FT                   /evidence="ECO:0000255"
FT   PROPEP          22..50
FT                   /evidence="ECO:0000269|PubMed:1390774"
FT                   /id="PRO_0000034889"
FT   PEPTIDE         51..69
FT                   /note="Alpha-conotoxin SII"
FT                   /evidence="ECO:0000269|PubMed:1390774"
FT                   /id="PRO_0000034890"
FT   PROPEP          70..72
FT                   /id="PRO_0000034891"
FT   REGION          23..51
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        26..48
FT                   /note="Basic and acidic residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   DISULFID        52..68
FT                   /evidence="ECO:0000269|PubMed:15707935,
FT                   ECO:0007744|PDB:6OTB"
FT   DISULFID        53..58
FT                   /evidence="ECO:0000269|PubMed:15707935,
FT                   ECO:0007744|PDB:6OTB"
FT   DISULFID        54..64
FT                   /evidence="ECO:0000269|PubMed:15707935,
FT                   ECO:0007744|PDB:6OTB"
FT   CONFLICT        23
FT                   /note="P -> T (in Ref. 1; no nucleotide entry)"
FT                   /evidence="ECO:0000305"
FT   CONFLICT        72
FT                   /note="L -> I (in Ref. 2; AAN77902)"
FT                   /evidence="ECO:0000305"
FT   HELIX           56..58
FT                   /evidence="ECO:0007829|PDB:6OTB"
SQ   SEQUENCE   72 AA;  7830 MW;  521191749F4A94CF CRC64;
     MGMRMMFTVF LLVVLATTVV SFPSDRASDG RDDEAKDERS DMHESDRNGR GCCCNPACGP
     NYGCGTSCSR TL