ID   CIRC_CHAPA              Reviewed;          30 AA.
AC   P84641;
DT   13-SEP-2005, integrated into UniProtKB/Swiss-Prot.
DT   13-SEP-2005, sequence version 1.
DT   25-MAY-2022, entry version 38.
DE   RecName: Full=Circulin-C;
DE            Short=CIRC;
OS   Chassalia parviflora.
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Gentianales; Rubiaceae; Rubioideae; Palicoureeae;
OC   Chassalia.
OX   NCBI_TaxID=58431;
RN   [1] {ECO:0000305}
RP   PROTEIN SEQUENCE, FUNCTION, AND MASS SPECTROMETRY.
RC   TISSUE=Stem {ECO:0000269|PubMed:10691702};
RX   PubMed=10691702; DOI=10.1021/np990432r;
RA   Gustafson K.R., Walton L.K., Sowder R.C. Jr., Johnson D.G., Pannell L.K.,
RA   Cardellina J.H. Jr., Boyd M.R.;
RT   "New circulin macrocyclic polypeptides from Chassalia parvifolia.";
RL   J. Nat. Prod. 63:176-178(2000).
CC   -!- FUNCTION: Probably participates in a plant defense mechanism. Inhibits
CC       the cytopathic effects of the human immunodeficiency virus.
CC       {ECO:0000255|PROSITE-ProRule:PRU00395, ECO:0000269|PubMed:10691702,
CC       ECO:0000305}.
CC   -!- DOMAIN: The presence of a 'disulfide through disulfide knot'
CC       structurally defines this protein as a knottin.
CC       {ECO:0000250|UniProtKB:P56871}.
CC   -!- PTM: This is a cyclic peptide. {ECO:0000255|PROSITE-ProRule:PRU00395,
CC       ECO:0000269|PubMed:10691702}.
CC   -!- MASS SPECTROMETRY: Mass=3102.3; Method=FAB;
CC       Evidence={ECO:0000269|PubMed:10691702};
CC   -!- SIMILARITY: Belongs to the cyclotide family. Bracelet subfamily.
CC       {ECO:0000255|PROSITE-ProRule:PRU00395}.
CC   -!- CAUTION: This peptide is cyclic. The start position was chosen by
CC       similarity to OAK1 (kalata-B1) for which the DNA sequence is known.
CC       {ECO:0000305}.
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DR   AlphaFoldDB; P84641; -.
DR   SMR; P84641; -.
DR   GO; GO:0006952; P:defense response; IDA:UniProtKB.
DR   GO; GO:0050688; P:regulation of defense response to virus; IEA:UniProtKB-KW.
DR   InterPro; IPR005535; Cyclotide.
DR   InterPro; IPR012323; Cyclotide_bracelet_CS.
DR   InterPro; IPR036146; Cyclotide_sf.
DR   Pfam; PF03784; Cyclotide; 1.
DR   PIRSF; PIRSF037891; Cycloviolacin; 1.
DR   SUPFAM; SSF57038; SSF57038; 1.
DR   PROSITE; PS51052; CYCLOTIDE; 1.
DR   PROSITE; PS60008; CYCLOTIDE_BRACELET; 1.
PE   1: Evidence at protein level;
KW   Antiviral protein; Direct protein sequencing; Disulfide bond; Knottin;
KW   Plant defense.
FT   PEPTIDE         1..30
FT                   /note="Circulin-C"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00395,
FT                   ECO:0000269|PubMed:10691702"
FT                   /id="PRO_0000043600"
FT   DISULFID        4..20
FT                   /evidence="ECO:0000250|UniProtKB:P56871,
FT                   ECO:0000255|PROSITE-ProRule:PRU00395"
FT   DISULFID        8..22
FT                   /evidence="ECO:0000250|UniProtKB:P56871,
FT                   ECO:0000255|PROSITE-ProRule:PRU00395"
FT   DISULFID        13..27
FT                   /evidence="ECO:0000250|UniProtKB:P56871,
FT                   ECO:0000255|PROSITE-ProRule:PRU00395"
FT   CROSSLNK        1..30
FT                   /note="Cyclopeptide (Gly-Asn)"
FT                   /evidence="ECO:0000269|PubMed:10691702"
SQ   SEQUENCE   30 AA;  3126 MW;  B9819A52FC9BA4E3 CRC64;
     GIPCGESCVF IPCITSVAGC SCKSKVCYRN