ID   CYTL_TACTR              Reviewed;         133 AA.
AC   Q7M429;
DT   10-MAY-2004, integrated into UniProtKB/Swiss-Prot.
DT   15-DEC-2003, sequence version 1.
DT   25-MAY-2022, entry version 57.
DE   RecName: Full=L-cystatin;
DE   Flags: Precursor;
OS   Tachypleus tridentatus (Japanese horseshoe crab).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Chelicerata; Merostomata;
OC   Xiphosura; Limulidae; Tachypleus.
OX   NCBI_TaxID=6853;
RN   [1]
RP   NUCLEOTIDE SEQUENCE, PROTEIN SEQUENCE OF 26-57; 60-105; 107-113 AND
RP   115-128, CHARACTERIZATION, SUBCELLULAR LOCATION, AND TISSUE SPECIFICITY.
RX   PubMed=8907180; DOI=10.1093/oxfordjournals.jbchem.a021220;
RA   Agarwala K.L., Kawabata S., Hirata M., Miyagi M., Tsunasawa S., Iwanaga S.;
RT   "A cysteine protease inhibitor stored in the large granules of horseshoe
RT   crab hemocytes: purification, characterization, cDNA cloning and tissue
RT   localization.";
RL   J. Biochem. 119:85-94(1996).
CC   -!- FUNCTION: Tight-binding inhibitor for papain. It has an important role
CC       in the protection of cells, antimicrobial activity against Gram-
CC       negative bacteria, defense against invading microbes, and response to
CC       external stimuli.
CC   -!- SUBCELLULAR LOCATION: Cytoplasmic granule {ECO:0000269|PubMed:8907180}.
CC       Note=Large granules of hemocytes.
CC   -!- TISSUE SPECIFICITY: Expressed in hemocytes and slightly in heart.
CC       {ECO:0000269|PubMed:8907180}.
CC   -!- SIMILARITY: Belongs to the cystatin family. {ECO:0000305}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   PIR; JC4536; JC4536.
DR   AlphaFoldDB; Q7M429; -.
DR   SMR; Q7M429; -.
DR   GO; GO:0004869; F:cysteine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   GO; GO:0042742; P:defense response to bacterium; 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   Antibiotic; Antimicrobial; Direct protein sequencing; Disulfide bond;
KW   Protease inhibitor; Pyrrolidone carboxylic acid; Signal;
KW   Thiol protease inhibitor.
FT   SIGNAL          1..19
FT                   /evidence="ECO:0000255"
FT   CHAIN           20..133
FT                   /note="L-cystatin"
FT                   /id="PRO_0000006667"
FT   MOTIF           67..71
FT                   /note="Secondary area of contact"
FT                   /evidence="ECO:0000250"
FT   SITE            23
FT                   /note="Reactive site"
FT                   /evidence="ECO:0000250"
FT   MOD_RES         20
FT                   /note="Pyrrolidone carboxylic acid"
FT                   /evidence="ECO:0000255"
FT   DISULFID        85..98
FT                   /evidence="ECO:0000250"
FT   DISULFID        109..129
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   133 AA;  14691 MW;  F708FB902AF2D38F CRC64;
     MEGYNILAVL IILVGVSMGQ IPGGWIDANV GDTDVKEAAR FATEAQSSRS NSLYHHKLLK
     IHKARTQVVS GINYEVFIET GTTTCKKSEV PLEDLKRCAV PENGVKHLCQ AIVWVQAWIP
     RTKVTKLECQ NKG