ID   CM3B_CONGE              Reviewed;          22 AA.
AC   P01524;
DT   21-JUL-1986, integrated into UniProtKB/Swiss-Prot.
DT   21-JUL-1986, sequence version 1.
DT   25-MAY-2022, entry version 97.
DE   RecName: Full=Mu-conotoxin GIIIB {ECO:0000303|PubMed:2410412};
DE   AltName: Full=Geographutoxin II {ECO:0000303|PubMed:6852238};
DE            Short=GTx-II {ECO:0000303|PubMed:6852238};
DE   AltName: Full=Myotoxin II;
OS   Conus geographus (Geography cone) (Nubecula geographus).
OC   Eukaryota; Metazoa; Spiralia; Lophotrochozoa; Mollusca; Gastropoda;
OC   Caenogastropoda; Neogastropoda; Conoidea; Conidae; Conus; Gastridium.
OX   NCBI_TaxID=6491;
RN   [1]
RP   PROTEIN SEQUENCE, HYDROXYLATION AT PRO-6; PRO-7 AND PRO-17, AMIDATION AT
RP   ALA-22, AND SUBCELLULAR LOCATION.
RX   PubMed=2410412; DOI=10.1016/s0021-9258(17)39364-x;
RA   Cruz L.J., Gray W.R., Olivera B.M., Zeikus R.D., Kerr L., Yoshikami D.,
RA   Moczydlowski E.;
RT   "Conus geographus toxins that discriminate between neuronal and muscle
RT   sodium channels.";
RL   J. Biol. Chem. 260:9280-9288(1985).
RN   [2]
RP   PROTEIN SEQUENCE, AND SUBCELLULAR LOCATION.
RX   PubMed=6852238; DOI=10.1016/0014-5793(82)80620-0;
RA   Sato S., Nakamura H., Ohizumi Y., Kobayashi J., Hirata Y.;
RT   "The amino acid sequences of homologous hydroxyproline-containing myotoxins
RT   from the marine snail Conus geographus venom.";
RL   FEBS Lett. 155:277-280(1983).
RN   [3]
RP   STRUCTURE BY NMR, AND DISULFIDE BONDS.
RX   PubMed=8688418; DOI=10.1021/bi960073o;
RA   Hill J.M., Alewood P.F., Craik D.J.;
RT   "Three-dimensional solution structure of mu-conotoxin GIIIB, a specific
RT   blocker of skeletal muscle sodium channels.";
RL   Biochemistry 35:8824-8835(1996).
CC   -!- FUNCTION: Mu-conotoxins block voltage-gated sodium channels (Nav).
CC       {ECO:0000250|UniProtKB:P01523}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000269|PubMed:6852238,
CC       ECO:0000269|PubMed:8688418}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom duct.
CC       {ECO:0000305|PubMed:6852238, ECO:0000305|PubMed:8688418}.
CC   -!- DOMAIN: The cysteine framework is III (CC-C-C-CC). Classified in the M-
CC       4 branch, since 4 residues stand between the fourth and the fifth
CC       cysteine residues. {ECO:0000305}.
CC   -!- SIMILARITY: Belongs to the conotoxin M superfamily. {ECO:0000305}.
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DR   PIR; A01787; MXKN2.
DR   PDB; 1GIB; NMR; -; A=1-22.
DR   PDBsum; 1GIB; -.
DR   AlphaFoldDB; P01524; -.
DR   SMR; P01524; -.
DR   ConoServer; 1566; GIIIB.
DR   EvolutionaryTrace; P01524; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0019871; F:sodium channel inhibitor activity; IEA:InterPro.
DR   GO; GO:0090729; F:toxin activity; IEA:UniProtKB-KW.
DR   InterPro; IPR008036; Conotoxin_mu-typ.
DR   Pfam; PF05374; Mu-conotoxin; 1.
DR   PROSITE; PS60013; MU_CONOTOXIN; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Amidation; Direct protein sequencing; Disulfide bond;
KW   Hydroxylation; Ion channel impairing toxin; Neurotoxin; Secreted; Toxin;
KW   Voltage-gated sodium channel impairing toxin.
FT   PEPTIDE         1..22
FT                   /note="Mu-conotoxin GIIIB"
FT                   /evidence="ECO:0000269|PubMed:2410412,
FT                   ECO:0000269|PubMed:6852238"
FT                   /id="PRO_0000044494"
FT   MOD_RES         6
FT                   /note="4-hydroxyproline; partial"
FT                   /evidence="ECO:0000269|PubMed:2410412"
FT   MOD_RES         7
FT                   /note="4-hydroxyproline; partial"
FT                   /evidence="ECO:0000269|PubMed:2410412"
FT   MOD_RES         17
FT                   /note="4-hydroxyproline"
FT                   /evidence="ECO:0000269|PubMed:2410412"
FT   MOD_RES         22
FT                   /note="Alanine amide"
FT                   /evidence="ECO:0000269|PubMed:2410412"
FT   DISULFID        3..15
FT                   /evidence="ECO:0000269|PubMed:8688418,
FT                   ECO:0007744|PDB:1GIB"
FT   DISULFID        4..20
FT                   /evidence="ECO:0000269|PubMed:8688418,
FT                   ECO:0007744|PDB:1GIB"
FT   DISULFID        10..21
FT                   /evidence="ECO:0000269|PubMed:8688418,
FT                   ECO:0007744|PDB:1GIB"
FT   STRAND          3..7
FT                   /evidence="ECO:0007829|PDB:1GIB"
FT   HELIX           13..15
FT                   /evidence="ECO:0007829|PDB:1GIB"
FT   TURN            19..21
FT                   /evidence="ECO:0007829|PDB:1GIB"
SQ   SEQUENCE   22 AA;  2599 MW;  F50402BA93199E01 CRC64;
     RDCCTPPRKC KDRRCKPMKC CA