ID   CYT_COTJA               Reviewed;         116 AA.
AC   P81061;
DT   15-JUL-1998, integrated into UniProtKB/Swiss-Prot.
DT   15-JUL-1998, sequence version 1.
DT   03-AUG-2022, entry version 76.
DE   RecName: Full=Cystatin;
DE   AltName: Full=Egg-white cystatin;
OS   Coturnix japonica (Japanese quail) (Coturnix coturnix japonica).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Archelosauria; Archosauria; Dinosauria; Saurischia; Theropoda;
OC   Coelurosauria; Aves; Neognathae; Galloanserae; Galliformes; Phasianidae;
OC   Perdicinae; Coturnix.
OX   NCBI_TaxID=93934;
RN   [1]
RP   PROTEIN SEQUENCE, PHOSPHORYLATION AT SER-80, AND IDENTIFICATION BY MASS
RP   SPECTROMETRY.
RC   TISSUE=Egg white;
RX   PubMed=9276465; DOI=10.1016/s0014-5793(97)00806-5;
RA   Gerhartz B., Engh R.A., Mentele R., Eckerskorn C., Torquato R., Wittman J.,
RA   Kolb H.J., Machleidt W., Fritz H., Auerswald E.A.;
RT   "Quail cystatin: isolation and characterisation of a new member of the
RT   cystatin family and its hypothetical interaction with cathepsin B.";
RL   FEBS Lett. 412:551-558(1997).
CC   -!- FUNCTION: This protein binds tightly to and inhibits papain and
CC       cathepsin B.
CC   -!- SUBCELLULAR LOCATION: Secreted.
CC   -!- SIMILARITY: Belongs to the cystatin family. {ECO:0000305}.
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DR   AlphaFoldDB; P81061; -.
DR   SMR; P81061; -.
DR   MEROPS; I25.011; -.
DR   iPTMnet; P81061; -.
DR   Proteomes; UP000694412; Unplaced.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0004869; F:cysteine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   CDD; cd00042; CY; 1.
DR   InterPro; IPR000010; Cystatin_dom.
DR   InterPro; IPR046350; Cystatin_sf.
DR   InterPro; IPR018073; Prot_inh_cystat_CS.
DR   Pfam; PF00031; Cystatin; 1.
DR   SMART; SM00043; CY; 1.
DR   SUPFAM; SSF54403; SSF54403; 1.
DR   PROSITE; PS00287; CYSTATIN; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Disulfide bond; Phosphoprotein;
KW   Protease inhibitor; Reference proteome; Secreted; Thiol protease inhibitor.
FT   CHAIN           1..116
FT                   /note="Cystatin"
FT                   /id="PRO_0000207151"
FT   MOTIF           53..57
FT                   /note="Secondary area of contact"
FT   SITE            9
FT                   /note="Reactive site"
FT   MOD_RES         80
FT                   /note="Phosphoserine"
FT                   /evidence="ECO:0000269|PubMed:9276465"
FT   DISULFID        71..81
FT   DISULFID        95..115
SQ   SEQUENCE   116 AA;  13093 MW;  48248621053A2F70 CRC64;
     SEGRSRLLGA PVPVRENDEG LQRALQFAMA EYNKASNDKY SSRVVRIISA KQQLVSGIKY
     IMEVEIGRTT CPKSSADLQS CEFHDEPEMA KYTTCNFVVY SIPWLNQIKL LKSSCQ