ID   CPI4_SOLTU              Reviewed;          22 AA.
AC   P58602;
DT   23-JAN-2002, integrated into UniProtKB/Swiss-Prot.
DT   23-JAN-2002, sequence version 1.
DT   03-AUG-2022, entry version 52.
DE   RecName: Full=Cysteine protease inhibitor 4;
DE   AltName: Full=PCPI-23;
DE   Flags: Fragment;
OS   Solanum tuberosum (Potato).
OC   Eukaryota; Viridiplantae; Streptophyta; Embryophyta; Tracheophyta;
OC   Spermatophyta; Magnoliopsida; eudicotyledons; Gunneridae; Pentapetalae;
OC   asterids; lamiids; Solanales; Solanaceae; Solanoideae; Solaneae; Solanum.
OX   NCBI_TaxID=4113;
RN   [1]
RP   PROTEIN SEQUENCE OF N-TERMINUS.
RC   STRAIN=cv. Istrinskii;
RX   PubMed=9598993; DOI=10.1016/s0014-5793(98)00321-4;
RA   Valueva T.A., Revina T.A., Kladnitskaya G.V., Mosolov V.V.;
RT   "Kunitz-type proteinase inhibitors from intact and Phytophthora-infected
RT   potato tubers.";
RL   FEBS Lett. 426:131-134(1998).
CC   -!- FUNCTION: Inhibitor of papain (cysteine protease). Does not inhibit
CC       trypsin, chymotrypsin nor elastase (serine proteases). May protect the
CC       plant by inhibiting proteases of invading organisms.
CC   -!- SUBCELLULAR LOCATION: Vacuole {ECO:0000250}.
CC   -!- TISSUE SPECIFICITY: Tubers.
CC   -!- MISCELLANEOUS: Does not accumulate in tubers infected with Phytophthora
CC       infestans.
CC   -!- MISCELLANEOUS: Has a single chain structure.
CC   -!- SIMILARITY: Belongs to the protease inhibitor I3 (leguminous Kunitz-
CC       type inhibitor) family. {ECO:0000305}.
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DR   AlphaFoldDB; P58602; -.
DR   STRING; 4113.PGSC0003DMT400026364; -.
DR   PRIDE; P58602; -.
DR   ProMEX; P58602; -.
DR   eggNOG; ENOG502R8RB; Eukaryota.
DR   Proteomes; UP000011115; Unassembled WGS sequence.
DR   GO; GO:0005773; C:vacuole; IEA:UniProtKB-SubCell.
DR   GO; GO:0004869; F:cysteine-type endopeptidase inhibitor activity; IEA:UniProtKB-KW.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Protease inhibitor; Reference proteome;
KW   Thiol protease inhibitor; Vacuole.
FT   CHAIN           1..>22
FT                   /note="Cysteine protease inhibitor 4"
FT                   /id="PRO_0000083316"
FT   NON_TER         22
SQ   SEQUENCE   22 AA;  2520 MW;  2F39C8A8A0138562 CRC64;
     PVLQVVRDIH GDILTPDSRY IL