ID   CYT2_CROAD              Reviewed;         136 AA.
AC   J3SE80;
DT   24-JUL-2013, integrated into UniProtKB/Swiss-Prot.
DT   31-OCT-2012, sequence version 1.
DT   25-MAY-2022, entry version 21.
DE   RecName: Full=Cystatin-2;
DE   Flags: Precursor;
OS   Crotalus adamanteus (Eastern diamondback rattlesnake).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Viperidae; Crotalinae; Crotalus.
OX   NCBI_TaxID=8729;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Venom gland;
RX   PubMed=23025625; DOI=10.1186/1471-2164-13-312;
RA   Rokyta D.R., Lemmon A.R., Margres M.J., Aronow K.;
RT   "The venom-gland transcriptome of the eastern diamondback rattlesnake
RT   (Crotalus adamanteus).";
RL   BMC Genomics 13:312-312(2012).
CC   -!- FUNCTION: Inhibits various C1 cysteine proteases including cathepsin L,
CC       papain and cathepsin B. This protein has no toxic activity and its
CC       function in the venom is unknown. It may play a role as housekeeping or
CC       regulatory protein (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC   -!- SIMILARITY: Belongs to the cystatin family. {ECO:0000305}.
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DR   EMBL; JU174280; AFJ49806.1; -; mRNA.
DR   AlphaFoldDB; J3SE80; -.
DR   SMR; J3SE80; -.
DR   MEROPS; I25.011; -.
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   2: Evidence at transcript level;
KW   Disulfide bond; Protease inhibitor; Secreted; Signal;
KW   Thiol protease inhibitor.
FT   SIGNAL          1..24
FT                   /evidence="ECO:0000255"
FT   CHAIN           25..136
FT                   /note="Cystatin-2"
FT                   /id="PRO_0000423039"
FT   DOMAIN          29..124
FT                   /note="Cystatin"
FT   MOTIF           73..77
FT                   /note="Secondary area of contact"
FT                   /evidence="ECO:0000250"
FT   SITE            29
FT                   /note="Reactive site"
FT                   /evidence="ECO:0000250"
FT   DISULFID        91..101
FT                   /evidence="ECO:0000250"
FT   DISULFID        115..135
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   136 AA;  15099 MW;  3693EDDDCB841B49 CRC64;
     MALLRGFLVC SLLLLSCICK EALGTRLLGG LENASPEEPG VARALQFAMN EYNRGSNDMY
     SSRVSEVVEA QKQIVSGIKY YFTVKIGRTV CRKGATDLEN CAFHNAPKLA QTMTCTFEVY
     NIPWRNFISL EKSSCT