ID   PSBU_CYAPA              Reviewed;         165 AA.
AC   Q5CC96;
DT   24-JUL-2007, integrated into UniProtKB/Swiss-Prot.
DT   12-APR-2005, sequence version 1.
DT   25-MAY-2022, entry version 32.
DE   RecName: Full=Photosystem II 12 kDa extrinsic protein, cyanelle;
DE   AltName: Full=PS II complex 12 kDa extrinsic protein;
DE   AltName: Full=PSII-U;
DE   Flags: Precursor;
GN   Name=psbU;
OS   Cyanophora paradoxa.
OC   Eukaryota; Glaucocystophyceae; Cyanophoraceae; Cyanophora.
OX   NCBI_TaxID=2762;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   STRAIN=UTEX LB 555 / Pringsheim;
RX   PubMed=15691332; DOI=10.1111/j.1742-4658.2004.04533.x;
RA   Steiner J.M., Berghoefer J., Yusa F., Pompe J.A., Kloesgen R.B.,
RA   Loeffelhardt W.;
RT   "Conservative sorting in a primitive plastid. The cyanelle of Cyanophora
RT   paradoxa.";
RL   FEBS J. 272:987-998(2005).
RN   [2]
RP   SUBUNIT, AND ASSOCIATION WITH THYLAKOIDS.
RX   PubMed=16176274; DOI=10.1111/j.1742-4658.2005.04912.x;
RA   Enami I., Suzuki T., Tada O., Nakada Y., Nakamura K., Tohri A., Ohta H.,
RA   Inoue I., Shen J.-R.;
RT   "Distribution of the extrinsic proteins as a potential marker for the
RT   evolution of photosynthetic oxygen-evolving photosystem II.";
RL   FEBS J. 272:5020-5030(2005).
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 and PsbV forms the oxygen-evolving complex of
CC       photosystem II. This protein is not detected by antibodies against
CC       green algal PsbU but it is detected by antibodies against red algal
CC       PsbU (PubMed:16176274). {ECO:0000269|PubMed:16176274}.
CC   -!- SUBCELLULAR LOCATION: Plastid, cyanelle thylakoid membrane
CC       {ECO:0000305}; Peripheral membrane protein {ECO:0000305}; Lumenal side
CC       {ECO:0000305}. Note=Associated with photosystem II at the lumenal side
CC       of the thylakoid membrane. {ECO:0000305}.
CC   -!- PTM: Might be translocated into the thylakoid lumen by the Tat system.
CC       The position of the transit peptide cleavages have not been
CC       experimentally proven.
CC   -!- SIMILARITY: Belongs to the PsbU family. {ECO:0000305}.
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DR   EMBL; AJ784849; CAH04957.1; -; mRNA.
DR   AlphaFoldDB; Q5CC96; -.
DR   SMR; Q5CC96; -.
DR   GO; GO:0033115; C:cyanelle thylakoid membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0019898; C:extrinsic component of membrane; IEA:InterPro.
DR   GO; GO:0009654; C:photosystem II oxygen evolving complex; IEA:InterPro.
DR   GO; GO:0015979; P:photosynthesis; IEA:UniProtKB-KW.
DR   GO; GO:0042549; P:photosystem II stabilization; IEA:InterPro.
DR   InterPro; IPR010527; PSII_PsbU.
DR   Pfam; PF06514; PsbU; 1.
PE   1: Evidence at protein level;
KW   Cyanelle; Electron transport; Membrane; Photosynthesis; Photosystem II;
KW   Plastid; Thylakoid; Transit peptide; Transport.
FT   TRANSIT         1..45
FT                   /note="Cyanelle"
FT                   /evidence="ECO:0000255"
FT   TRANSIT         46..65
FT                   /note="Thylakoid"
FT                   /evidence="ECO:0000255"
FT   CHAIN           66..165
FT                   /note="Photosystem II 12 kDa extrinsic protein, cyanelle"
FT                   /id="PRO_0000295789"
SQ   SEQUENCE   165 AA;  17457 MW;  E34C4D000723EFA3 CRC64;
     MAFVASIPAV RIQTSLQSLK GESLKAQKPA AAKQAAFTVV AQAEEKKGRR EFVAAAGALF
     AAFAASPAAF AYSAADANVT GLGGDLSNID INNANIAVYQ KLPGMYPNIA KKIIGGAPYK
     SVAELYSLDL SEKQKETLRK YEDNFYAGEP VDALGFDSIN NGIYK