ID   CATB3_GIAIN             Reviewed;         299 AA.
AC   P92133; Q9GP23;
DT   16-JUN-2003, integrated into UniProtKB/Swiss-Prot.
DT   16-JUN-2003, sequence version 2.
DT   03-AUG-2022, entry version 80.
DE   RecName: Full=Cathepsin B-like CP3;
DE            EC=3.4.22.-;
DE   AltName: Full=Cathepsin B-like protease B3;
DE   Flags: Precursor;
GN   Name=CP3;
OS   Giardia intestinalis (Giardia lamblia).
OC   Eukaryota; Metamonada; Diplomonadida; Hexamitidae; Giardiinae; Giardia.
OX   NCBI_TaxID=5741;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA], FUNCTION, SUBCELLULAR LOCATION, AND
RP   DEVELOPMENTAL STAGE.
RC   STRAIN=ATCC 30957 / WB;
RX   PubMed=9150143; DOI=10.1016/s0092-8674(00)80224-x;
RA   Ward W., Alvarado L., Rawlings N.D., Engel J.C., Franklin C.,
RA   McKerrow J.H.;
RT   "A primitive enzyme for a primitive cell: the protease required for
RT   excystation of Giardia.";
RL   Cell 89:437-444(1997).
RN   [2]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA].
RC   STRAIN=ATCC 30957 / WB;
RX   PubMed=11849701; DOI=10.1016/s0166-6851(01)00438-8;
RA   Sajid M., McKerrow J.H.;
RT   "Cysteine proteases of parasitic organisms.";
RL   Mol. Biochem. Parasitol. 120:1-21(2002).
CC   -!- FUNCTION: Thiol protease which is required for parasite excystation and
CC       invasion of the proximal small intestine of the human host.
CC       {ECO:0000269|PubMed:9150143}.
CC   -!- SUBCELLULAR LOCATION: Vacuole {ECO:0000269|PubMed:9150143}.
CC   -!- DEVELOPMENTAL STAGE: To initiate infection, trophozoites emerge from a
CC       cyst in the host. Excystation is blocked by specific cysteine protease
CC       inhibitors. Vacuoles release it just prior to excystation. Expressed in
CC       replicating and encysting trophozoites without supplemental iron.
CC       {ECO:0000269|PubMed:9150143}.
CC   -!- SIMILARITY: Belongs to the peptidase C1 family. {ECO:0000255|PROSITE-
CC       ProRule:PRU10088, ECO:0000255|PROSITE-ProRule:PRU10089,
CC       ECO:0000255|PROSITE-ProRule:PRU10090}.
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DR   EMBL; U83277; AAB58260.1; -; Genomic_DNA.
DR   EMBL; AJ302013; CAC18648.1; -; Genomic_DNA.
DR   AlphaFoldDB; P92133; -.
DR   SMR; P92133; -.
DR   MEROPS; C01.094; -.
DR   PRIDE; P92133; -.
DR   VEuPathDB; GiardiaDB:DHA2_16779; -.
DR   VEuPathDB; GiardiaDB:GL50581_78; -.
DR   VEuPathDB; GiardiaDB:GL50803_0016779; -.
DR   eggNOG; KOG1543; Eukaryota.
DR   GO; GO:0005773; C:vacuole; IEA:UniProtKB-SubCell.
DR   GO; GO:0008234; F:cysteine-type peptidase activity; IEA:UniProtKB-KW.
DR   GO; GO:0006508; P:proteolysis; IEA:UniProtKB-KW.
DR   InterPro; IPR038765; Papain-like_cys_pep_sf.
DR   InterPro; IPR025661; Pept_asp_AS.
DR   InterPro; IPR000169; Pept_cys_AS.
DR   InterPro; IPR025660; Pept_his_AS.
DR   InterPro; IPR000668; Peptidase_C1A_C.
DR   Pfam; PF00112; Peptidase_C1; 1.
DR   PRINTS; PR00705; PAPAIN.
DR   SMART; SM00645; Pept_C1; 1.
DR   SUPFAM; SSF54001; SSF54001; 1.
DR   PROSITE; PS00640; THIOL_PROTEASE_ASN; 1.
DR   PROSITE; PS00139; THIOL_PROTEASE_CYS; 1.
DR   PROSITE; PS00639; THIOL_PROTEASE_HIS; 1.
PE   2: Evidence at transcript level;
KW   Disulfide bond; Hydrolase; Protease; Signal; Thiol protease; Vacuole;
KW   Zymogen.
FT   SIGNAL          1..19
FT                   /evidence="ECO:0000255"
FT   PROPEP          20..?
FT                   /note="Activation peptide"
FT                   /evidence="ECO:0000250"
FT                   /id="PRO_0000026168"
FT   CHAIN           ?..299
FT                   /note="Cathepsin B-like CP3"
FT                   /id="PRO_0000026169"
FT   ACT_SITE        100
FT                   /evidence="ECO:0000250"
FT   ACT_SITE        244
FT                   /evidence="ECO:0000250"
FT   ACT_SITE        265
FT                   /evidence="ECO:0000250"
FT   DISULFID        87..114
FT                   /evidence="ECO:0000250"
FT   DISULFID        97..140
FT                   /evidence="ECO:0000250"
FT   DISULFID        133..176
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   299 AA;  32674 MW;  2FD71397C86EA987 CRC64;
     MKLFLLAAAA FSAPALTVSE LNHIKSLNPR WKAGIPKRFE GLTKDEISSL LMPVSFLKRD
     RAAVPRGTVS ATQAPDSFDF REEYPHCIPE VVDQGGCGSC WAFSSVASVG DRRCFAGLDK
     KAVKYSPQYV VSCDRGDMAC DGGWLPSVWR FLTKTGTTTD ECVPYQSGST GARGTCPTKC
     ADGSDLPHLY KATKAVDYGL DAPAIMKALA TGGPLQTAFT VYSDFMYYES GVYQHTYGRV
     EGGHAVDMVG YGTDDDGVDY WIIKNSWGPD WGEDGYFRII RMTNECGIEE QVIGGFFEN