ID   CYT_BITGA               Reviewed;         140 AA.
AC   Q6T6T4;
DT   26-FEB-2008, integrated into UniProtKB/Swiss-Prot.
DT   05-JUL-2004, sequence version 1.
DT   25-MAY-2022, entry version 50.
DE   RecName: Full=Bitiscystatin;
DE            Short=Cystatin;
DE   Flags: Precursor;
OS   Bitis gabonica (Gaboon adder) (Gaboon viper).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Lepidosauria; Squamata; Bifurcata; Unidentata; Episquamata; Toxicofera;
OC   Serpentes; Colubroidea; Viperidae; Viperinae; Bitis.
OX   NCBI_TaxID=8694;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE MRNA].
RC   TISSUE=Venom gland;
RX   PubMed=15276202; DOI=10.1016/j.gene.2004.03.024;
RA   Francischetti I.M.B., My-Pham V., Harrison J., Garfield M.K.,
RA   Ribeiro J.M.C.;
RT   "Bitis gabonica (Gaboon viper) snake venom gland: toward a catalog for the
RT   full-length transcripts (cDNA) and proteins.";
RL   Gene 337:55-69(2004).
RN   [2]
RP   PROTEIN SEQUENCE OF 27-41, SUBCELLULAR LOCATION, TISSUE SPECIFICITY, AND
RP   IDENTIFICATION BY MASS SPECTROMETRY.
RC   TISSUE=Venom;
RX   PubMed=17203976; DOI=10.1021/pr060494k;
RA   Calvete J.J., Marcinkiewicz C., Sanz L.;
RT   "Snake venomics of Bitis gabonica gabonica. Protein family composition,
RT   subunit organization of venom toxins, and characterization of dimeric
RT   disintegrins bitisgabonin-1 and bitisgabonin-2.";
RL   J. Proteome Res. 6:326-336(2007).
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:0000269|PubMed:17203976}.
CC   -!- TISSUE SPECIFICITY: Expressed by the venom gland.
CC       {ECO:0000269|PubMed:17203976}.
CC   -!- SIMILARITY: Belongs to the cystatin family. {ECO:0000305}.
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DR   EMBL; AY430403; AAR24527.1; -; mRNA.
DR   AlphaFoldDB; Q6T6T4; -.
DR   SMR; Q6T6T4; -.
DR   MEROPS; I25.012; -.
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; Protease inhibitor; Secreted;
KW   Signal; Thiol protease inhibitor.
FT   SIGNAL          1..26
FT                   /evidence="ECO:0000269|PubMed:17203976"
FT   CHAIN           27..140
FT                   /note="Bitiscystatin"
FT                   /id="PRO_0000319471"
FT   DOMAIN          29..129
FT                   /note="Cystatin"
FT   MOTIF           73..77
FT                   /note="Secondary area of contact"
FT   SITE            29
FT                   /note="Reactive site"
FT                   /evidence="ECO:0000250"
FT   DISULFID        91..107
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   140 AA;  15900 MW;  771DA8853F7D7CE9 CRC64;
     MHSRLLVAAP HCLLLLLLLP SALPALKVGG LYPRDVMDPE VQEAAAFAVE NYNAQSTNDN
     YFKARRIVEA QSQVVSGVKY YLKMELAKTT CKKIAGKPKL YQEIQNCNLP PENQQEEITC
     HFEVWSRPWL QKTVLTKDEL