ID   CYTB_PAROL              Reviewed;          98 AA.
AC   B2Z449;
DT   11-NOV-2015, integrated into UniProtKB/Swiss-Prot.
DT   01-JUL-2008, sequence version 1.
DT   25-MAY-2022, entry version 28.
DE   RecName: Full=Cystatin-B {ECO:0000250|UniProtKB:P04080, ECO:0000312|EMBL:ACC86114.1};
DE   AltName: Full=PoCystatin-B {ECO:0000250|UniProtKB:P04080, ECO:0000303|PubMed:23648289};
DE   AltName: Full=Stefin-B {ECO:0000250|UniProtKB:P04080, ECO:0000303|PubMed:23648289};
OS   Paralichthys olivaceus (Bastard halibut) (Hippoglossus olivaceus).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Actinopterygii; Neopterygii; Teleostei; Neoteleostei; Acanthomorphata;
OC   Carangaria; Pleuronectiformes; Pleuronectoidei; Paralichthyidae;
OC   Paralichthys.
OX   NCBI_TaxID=8255;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA], FUNCTION, ACTIVITY REGULATION,
RP   BIOPHYSICOCHEMICAL PROPERTIES, TISSUE SPECIFICITY, INDUCTION, AND
RP   PHYLOGENETIC ANALYSIS.
RX   PubMed=23648289; DOI=10.1016/j.cbpb.2013.04.007;
RA   Ahn S.J., Bak H.J., Park J.H., Kim S.A., Kim N.Y., Lee J.Y., Sung J.H.,
RA   Jeon S.J., Chung J.K., Lee H.H.;
RT   "Olive flounder (Paralichthys olivaceus) cystatin B: Cloning, tissue
RT   distribution, expression and inhibitory profile of piscine cystatin B.";
RL   Comp. Biochem. Physiol. 165:211-218(2013).
CC   -!- FUNCTION: Thiol protease inhibitor. Has high papain, bovine cathepsin B
CC       and fish cathepsins F and X inhibitory activity and inhibits fish
CC       cathepsins L, S and K to a lesser extent in vitro. May be involved in
CC       innate immunity. {ECO:0000269|PubMed:23648289}.
CC   -!- ACTIVITY REGULATION: Greatly decreased inhibitory activity against
CC       papain protease by metal ions including ZnSO(4), CuSO(4), HgCl(2) and
CC       CoCl(2). Decreased inhibitory activity against papain protease by
CC       detergents including Tween 20, SDS and Brij 35.
CC       {ECO:0000269|PubMed:23648289}.
CC   -!- BIOPHYSICOCHEMICAL PROPERTIES:
CC       pH dependence:
CC         Optimum pH is 6-7.5 and pH 6.5-8 for papain and bovine cathepsin B,
CC         respectively. {ECO:0000269|PubMed:23648289};
CC       Temperature dependence:
CC         Stable between 20 and 40 degrees Celsius. Activity for papain drops
CC         rapidly over 60 degrees Celsius. Retains inhibitory activity against
CC         papain for 10 days at 37 and 30 degrees Celsius.
CC         {ECO:0000269|PubMed:23648289};
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250|UniProtKB:P04080}.
CC   -!- TISSUE SPECIFICITY: Ubiquitously expressed in normal and
CC       lipopolysaccharide (LPS)-stimulated tissues including brain, eye,
CC       gullet, heart, liver, muscle, stomach, kidney, spleen, pyloric ceca,
CC       intestine and gill. {ECO:0000269|PubMed:23648289}.
CC   -!- INDUCTION: By LPS. Slightly increased expression 24 hours post-
CC       injection in spleen and muscle. {ECO:0000269|PubMed:23648289}.
CC   -!- SIMILARITY: Belongs to the cystatin family. {ECO:0000305}.
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DR   EMBL; EU597232; ACC86114.1; -; mRNA.
DR   AlphaFoldDB; B2Z449; -.
DR   SMR; B2Z449; -.
DR   GO; GO:0005737; C:cytoplasm; ISS:UniProtKB.
DR   GO; GO:0004869; F:cysteine-type endopeptidase inhibitor activity; IDA:UniProtKB.
DR   GO; GO:0071220; P:cellular response to bacterial lipoprotein; IPI:UniProtKB.
DR   GO; GO:0045087; P:innate immune response; IEA:UniProtKB-KW.
DR   InterPro; IPR000010; Cystatin_dom.
DR   InterPro; IPR046350; Cystatin_sf.
DR   InterPro; IPR001713; Prot_inh_stefin.
DR   PANTHER; PTHR11414; PTHR11414; 1.
DR   Pfam; PF00031; Cystatin; 1.
DR   PRINTS; PR00295; STEFINA.
DR   SMART; SM00043; CY; 1.
DR   SUPFAM; SSF54403; SSF54403; 1.
PE   1: Evidence at protein level;
KW   Cytoplasm; Immunity; Innate immunity; Protease inhibitor;
KW   Thiol protease inhibitor.
FT   CHAIN           1..98
FT                   /note="Cystatin-B"
FT                   /id="PRO_0000434649"
FT   DOMAIN          4..83
FT                   /note="Cystatin"
FT                   /evidence="ECO:0000255"
FT   MOTIF           46..50
FT                   /note="Secondary area of contact"
FT                   /evidence="ECO:0000250|UniProtKB:P04080"
FT   SITE            4
FT                   /note="Reactive site"
FT                   /evidence="ECO:0000250|UniProtKB:P04080"
SQ   SEQUENCE   98 AA;  11066 MW;  BADB4BDF49844977 CRC64;
     MLCGGTSQPV DADEQIQKIC DSMKPHAEAQ AGKTFDVFVA KTYTTQCVPG TNYFIKVHVG
     GDEHVHLRVY KKLPCNGETL ELSKMLQDKR HHDPLEYF