ID   O164_CONST              Reviewed;          78 AA.
AC   Q9XZK3;
DT   29-AUG-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1999, sequence version 1.
DT   25-MAY-2022, entry version 70.
DE   RecName: Full=Omega-conotoxin-like SO-4;
DE            Short=Omega-conotoxin SO4;
DE   Flags: Precursor;
GN   Name=SO4;
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).
CC   -!- FUNCTION: Omega-conotoxins act at presynaptic membranes, they bind and
CC       block voltage-gated calcium channels (Cav). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom duct.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin. {ECO:0000250}.
CC   -!- DOMAIN: The cysteine framework is VI/VII (C-C-CC-C-C).
CC   -!- SIMILARITY: Belongs to the conotoxin O1 superfamily. {ECO:0000305}.
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DR   EMBL; AF146349; AAD31909.1; -; mRNA.
DR   AlphaFoldDB; Q9XZK3; -.
DR   SMR; Q9XZK3; -.
DR   ConoServer; 865; SO4 precursor.
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:0008200; F:ion channel inhibitor activity; IEA:InterPro.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   InterPro; IPR004214; Conotoxin.
DR   InterPro; IPR012321; Conotoxin_omega-typ_CS.
DR   Pfam; PF02950; Conotoxin; 1.
DR   PROSITE; PS60004; OMEGA_CONOTOXIN; 1.
PE   2: Evidence at transcript level;
KW   Calcium channel impairing toxin; Disulfide bond;
KW   Ion channel impairing toxin; Knottin; Neurotoxin; Presynaptic neurotoxin;
KW   Secreted; Signal; Toxin; Voltage-gated calcium channel impairing toxin.
FT   SIGNAL          1..22
FT                   /evidence="ECO:0000255"
FT   PROPEP          23..42
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000034934"
FT   PEPTIDE         43..78
FT                   /note="Omega-conotoxin-like SO-4"
FT                   /id="PRO_0000034935"
FT   DISULFID        46..62
FT                   /evidence="ECO:0000250"
FT   DISULFID        53..65
FT                   /evidence="ECO:0000250"
FT   DISULFID        61..72
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   78 AA;  8527 MW;  A391E1EF9210C6C8 CRC64;
     MKLTCMVIVA VLLLTACQLI TADDSRGTQK HRSLRSTTKV SKATDCIEAG NYCGPTVMKI
     CCGFCSPYSK ICMNYPKN