ID   PSBU_SYNY4              Reviewed;          16 AA.
AC   P80460;
DT   15-JUL-1998, integrated into UniProtKB/Swiss-Prot.
DT   15-JUL-1998, sequence version 1.
DT   25-MAY-2022, entry version 54.
DE   RecName: Full=Photosystem II 12 kDa extrinsic protein;
DE   AltName: Full=PS II complex 12 kDa extrinsic protein;
DE   AltName: Full=PSII-U;
DE   Flags: Fragment;
GN   Name=psbU;
OS   Synechocystis sp. (strain PCC 6714) (Aphanocapsa sp. (strain PCC 6714)).
OC   Bacteria; Cyanobacteria; Synechococcales; Merismopediaceae; Synechocystis;
OC   unclassified Synechocystis.
OX   NCBI_TaxID=1147;
RN   [1]
RP   PROTEIN SEQUENCE.
RA   Naterstad K., Synstad B., Sirevag R.;
RL   Submitted (SEP-1996) to UniProtKB.
CC   -!- FUNCTION: Stabilizes the structure of photosystem II oxygen-evolving
CC       complex (OEC), the ion environment of oxygen evolution and protects the
CC       OEC against heat-induced inactivation. {ECO:0000250}.
CC   -!- SUBUNIT: With PsbO,P,Q and V forms the oxygen-evolving complex of
CC       photosystem II. {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Cellular thylakoid membrane {ECO:0000250};
CC       Peripheral membrane protein {ECO:0000250}; Lumenal side {ECO:0000250}.
CC       Note=Associated with photosystem II at the lumenal side of the
CC       thylakoid membrane. {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the PsbU family. {ECO:0000305}.
CC   -!- CAUTION: Was originally (Ref.1) thought to be a malate dehydrogenase.
CC       {ECO:0000305}.
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DR   AlphaFoldDB; P80460; -.
DR   GO; GO:0009523; C:photosystem II; IEA:UniProtKB-KW.
DR   GO; GO:0031676; C:plasma membrane-derived thylakoid membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0015979; P:photosynthesis; IEA:UniProtKB-KW.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Electron transport; Membrane; Photosynthesis;
KW   Photosystem II; Thylakoid; Transport.
FT   CHAIN           1..>16
FT                   /note="Photosystem II 12 kDa extrinsic protein"
FT                   /id="PRO_0000219670"
FT   NON_TER         16
SQ   SEQUENCE   16 AA;  1780 MW;  61D1896F14E81984 CRC64;
     MLNAVDAKLT TDFGQR