ID   IPB1_YEASX              Reviewed;          75 AA.
AC   P0CT05; D6W1G3; P01095;
DT   26-JUN-2013, integrated into UniProtKB/Swiss-Prot.
DT   26-JUN-2013, sequence version 1.
DT   25-MAY-2022, entry version 45.
DE   RecName: Full=Protease B inhibitor 1;
DE   AltName: Full=Proteinase inhibitor I(B)1;
GN   Name=PBI2; OrderedLocusNames=YNL015W;
OS   Saccharomyces cerevisiae (Baker's yeast).
OC   Eukaryota; Fungi; Dikarya; Ascomycota; Saccharomycotina; Saccharomycetes;
OC   Saccharomycetales; Saccharomycetaceae; Saccharomyces.
OX   NCBI_TaxID=4932;
RN   [1]
RP   PROTEIN SEQUENCE OF 2-75, AND CLEAVAGE OF INITIATOR METHIONINE.
RC   STRAIN=Carlsbergensis;
RX   PubMed=393265; DOI=10.1016/0006-291x(79)91221-x;
RA   Maier K., Mueller H., Tesch R., Witt I., Holzer H.;
RT   "Amino acid sequence of yeast proteinase B inhibitor 1 and comparison with
RT   inhibitor 2.";
RL   Biochem. Biophys. Res. Commun. 91:1390-1398(1979).
RN   [2]
RP   ORIGIN OF SEQUENCE, AND SUBCELLULAR LOCATION.
RC   STRAIN=4228 / ATCC 9080 / CBS 2354 / DSM 70424 / NBRC 0565 / NCYC 74 / NRRL
RC   Y-1089;
RX   PubMed=1100120; DOI=10.1016/0304-4165(75)90155-5;
RA   Betz H.;
RT   "Levels and turnover of the proteinase B inhibitors in yeast.";
RL   Biochim. Biophys. Acta 404:142-151(1975).
RN   [3]
RP   ORIGIN OF SEQUENCE.
RC   STRAIN=4228 / ATCC 9080 / CBS 2354 / DSM 70424 / NBRC 0565 / NCYC 74 / NRRL
RC   Y-1089;
RX   PubMed=328499; DOI=10.1016/s0021-9258(19)63349-1;
RA   Buenning P., Holzer H.;
RT   "Natural occurrence and chemical modification of proteinase B inhibitors
RT   from yeast.";
RL   J. Biol. Chem. 252:5316-5323(1977).
RN   [4]
RP   FUNCTION.
RC   STRAIN=Carlsbergensis;
RX   PubMed=2015812; DOI=10.1111/j.1432-1033.1991.tb15874.x;
RA   Schu P., Wolf D.H.;
RT   "The proteinase yscB inhibitor (PBI2) gene of yeast and studies on the
RT   function of its protein product.";
RL   Eur. J. Biochem. 197:1-7(1991).
CC   -!- FUNCTION: Cytosolic inhibitor of vacuolar proteinase B (yscB), probably
CC       regulating protease B activity during limited proteolysis. PBI2 is a
CC       component of the LMA1 complex, which is involved in the facilitation of
CC       vesicle fusion such as homotypic vacuole and ER-derived COPII vesicle
CC       fusion with the Golgi (By similarity). {ECO:0000250,
CC       ECO:0000269|PubMed:2015812}.
CC   -!- SUBUNIT: Part of the heterodimeric LMA1 complex together with the
CC       thioredoxin II/TRX2. LMA1 binds to the ATPase SEC18 (By similarity).
CC       {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000269|PubMed:1100120}. Nucleus
CC       {ECO:0000250}.
CC   -!- MISCELLANEOUS: Originally, 2 inhibitors of protease B, inhibitor I(B)2
CC       and inhibitor I(B)1, have been isolated from commercial baker's yeast,
CC       which consists of both S.cerevisiae and S.carlsbergensis. It has been
CC       shown that S.cerevisiae only produces inhibitor 2, and S.carlsbergensis
CC       only produces inhibitor 1 (PubMed:328499). A sequence for inhibitor 2
CC       can be found in strain S288c (AC P0CT04). {ECO:0000305|PubMed:328499}.
CC   -!- SIMILARITY: Belongs to the protease inhibitor I9 family. {ECO:0000305}.
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DR   PIR; S16882; YBBY2.
DR   AlphaFoldDB; P0CT05; -.
DR   SMR; P0CT05; -.
DR   MINT; P0CT05; -.
DR   VEuPathDB; FungiDB:YNL015W; -.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0005634; C:nucleus; IEA:UniProtKB-SubCell.
DR   GO; GO:0004867; F:serine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
DR   GO; GO:0015031; P:protein transport; IEA:UniProtKB-KW.
DR   Gene3D; 3.30.70.80; -; 1.
DR   InterPro; IPR037045; S8pro/Inhibitor_I9_sf.
PE   1: Evidence at protein level;
KW   Cytoplasm; Direct protein sequencing; Nucleus; Phosphoprotein;
KW   Protease inhibitor; Protein transport; Serine protease inhibitor;
KW   Transport.
FT   INIT_MET        1
FT                   /note="Removed"
FT                   /evidence="ECO:0000269|PubMed:393265"
FT   CHAIN           2..75
FT                   /note="Protease B inhibitor 1"
FT                   /id="PRO_0000422802"
FT   MOD_RES         74
FT                   /note="Phosphothreonine"
FT                   /evidence="ECO:0000250|UniProtKB:P0CT04"
SQ   SEQUENCE   75 AA;  8589 MW;  515454D440A4C8A8 CRC64;
     MTKNFIVTLK KNTPDVEAKK FLDSVHHAGG SIVHKFDIIK GYTIKVPDVL HLNKLKEKHN
     DVIENVEEDK EVHTN