ID   GUR_GYMSY               Reviewed;          35 AA.
AC   P25810; Q9S8D1;
DT   01-MAY-1992, integrated into UniProtKB/Swiss-Prot.
DT   01-FEB-1994, sequence version 2.
DT   25-MAY-2022, entry version 94.
DE   RecName: Full=Gurmarin;
DE   AltName: Full=Sweet taste-suppressing peptide;
OS   Gymnema sylvestre (Gurmar) (Periploca sylvestris).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Gentianales; Apocynaceae; Asclepiadoideae; Marsdenieae;
OC   Gymnema.
OX   NCBI_TaxID=4068;
RN   [1]
RP   PROTEIN SEQUENCE, AND PYROGLUTAMATE FORMATION AT GLN-1.
RC   TISSUE=Leaf;
RX   PubMed=1607357; DOI=10.1093/oxfordjournals.jbchem.a123705;
RA   Kamei K., Takano R., Miyasaka A., Imoto T., Hara S.;
RT   "Amino acid sequence of sweet-taste-suppressing peptide (gurmarin) from the
RT   leaves of Gymnema sylvestre.";
RL   J. Biochem. 111:109-112(1992).
RN   [2]
RP   DISULFIDE BONDS.
RC   TISSUE=Leaf;
RX   PubMed=8534991; DOI=10.1271/bbb.59.1956;
RA   Ota M., Ariyoshi Y.;
RT   "Location of the disulfide bonds of the sweetness-suppressing polypeptide
RT   gurmarin.";
RL   Biosci. Biotechnol. Biochem. 59:1956-1957(1995).
RN   [3]
RP   STRUCTURE BY NMR, AND DISULFIDE BONDS.
RX   PubMed=7787425; DOI=10.1007/bf00211756;
RA   Arai K., Ishima R., Morikawa S., Miyasaka A., Imoto T., Yoshimura S.,
RA   Aimoto S., Akasaka K.;
RT   "Three-dimensional structure of gurmarin, a sweet taste-suppressing
RT   polypeptide.";
RL   J. Biomol. NMR 5:297-305(1995).
RN   [4]
RP   STRUCTURE BY NMR, AND DISULFIDE BONDS.
RX   PubMed=10491100; DOI=10.1046/j.1432-1327.1999.00659.x;
RA   Fletcher J.I., Dingley A.J., Smith R., Connor M., Christie M.J., King G.F.;
RT   "High-resolution solution structure of gurmarin, a sweet-taste-suppressing
RT   plant polypeptide.";
RL   Eur. J. Biochem. 264:525-533(1999).
CC   -!- FUNCTION: Suppresses strongly the sweet taste responses in the rat with
CC       high specificity to sucrose, glucose, glycine, and saccharin. This
CC       effect is reversible, but complete recovery of the suppressed responses
CC       required at least 3h. Gurmarin showed no effect or only a very weak
CC       effect on the sweet taste sensation in humans.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin.
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DR   PIR; JX0200; JX0200.
DR   PDB; 1C4E; NMR; -; A=1-35.
DR   PDB; 1GUR; NMR; -; A=2-35.
DR   PDB; 5OLL; X-ray; 1.45 A; A=2-35.
DR   PDBsum; 1C4E; -.
DR   PDBsum; 1GUR; -.
DR   PDBsum; 5OLL; -.
DR   AlphaFoldDB; P25810; -.
DR   BMRB; P25810; -.
DR   SMR; P25810; -.
DR   EvolutionaryTrace; P25810; -.
DR   InterPro; IPR009101; Gurmarin/antifun_pep.
DR   SUPFAM; SSF57048; SSF57048; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Direct protein sequencing; Disulfide bond; Knottin;
KW   Pyrrolidone carboxylic acid; Taste-modifying protein.
FT   PEPTIDE         1..35
FT                   /note="Gurmarin"
FT                   /id="PRO_0000044776"
FT   MOD_RES         1
FT                   /note="Pyrrolidone carboxylic acid"
FT                   /evidence="ECO:0000269|PubMed:1607357"
FT   DISULFID        3..18
FT   DISULFID        10..23
FT   DISULFID        17..33
FT   STRAND          8..11
FT                   /evidence="ECO:0007829|PDB:5OLL"
FT   TURN            12..14
FT                   /evidence="ECO:0007829|PDB:5OLL"
FT   STRAND          18..20
FT                   /evidence="ECO:0007829|PDB:1C4E"
FT   STRAND          22..25
FT                   /evidence="ECO:0007829|PDB:5OLL"
FT   STRAND          27..29
FT                   /evidence="ECO:0007829|PDB:5OLL"
FT   STRAND          31..34
FT                   /evidence="ECO:0007829|PDB:5OLL"
SQ   SEQUENCE   35 AA;  4232 MW;  661BD6FBAF504CB6 CRC64;
     QQCVKKDELC IPYYLDCCEP LECKKVNWWD HKCIG