ID   PHEA2_CHRSP             Reviewed;          70 AA.
AC   P23815;
DT   01-NOV-1991, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1991, sequence version 1.
DT   03-AUG-2022, entry version 76.
DE   RecName: Full=Phycocyanin-645 alpha-2 chain;
DE            Short=PC-645;
OS   Chroomonas sp.
OC   Eukaryota; Cryptophyceae; Pyrenomonadales; Chroomonadaceae; Chroomonas;
OC   unclassified Chroomonas.
OX   NCBI_TaxID=3029;
RN   [1]
RP   PROTEIN SEQUENCE.
RX   PubMed=2222853; DOI=10.1515/bchm3.1990.371.2.537;
RA   Sidler W., Nutt H., Kumpf B., Frank G., Suter F., Brenzel A., Wehrmeyer W.,
RA   Zuber H.;
RT   "The complete amino-acid sequence and the phylogenetic origin of
RT   phycocyanin-645 from the cryptophytan alga Chroomonas sp.";
RL   Biol. Chem. Hoppe-Seyler 371:537-547(1990).
RN   [2]
RP   PROTEIN SEQUENCE OF 1-54.
RX   PubMed=4005040; DOI=10.1515/bchm3.1985.366.1.233;
RA   Sidler W., Kumpf B., Suter F., Morisset W., Wehrmeyer W., Zuber H.;
RT   "Structural studies on cryptomonad biliprotein subunits. Two different
RT   alpha-subunits in Chroomonas phycocyanin-645 and Cryptomonas phycoerythrin-
RT   545.";
RL   Biol. Chem. Hoppe-Seyler 366:233-244(1985).
CC   -!- FUNCTION: Light-harvesting photosynthetic tetrapyrrole chromophore-
CC       protein from the phycobiliprotein complex. {ECO:0000305}.
CC   -!- SUBUNIT: Heterotetramer of 2 different alpha chains and 2 identical
CC       beta chains which form 2 alpha-beta heterodimers within the
CC       heterotetramer. {ECO:0000250|UniProtKB:U5T880}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast thylakoid membrane
CC       {ECO:0000305}; Peripheral membrane protein {ECO:0000305}; Lumenal side
CC       {ECO:0000305}.
CC   -!- PTM: Contains one phycocyanobilin chromophore, one mesobiliverdin
CC       chromophore and one 15,16-dihydrobiliverdin chromophore with binding
CC       mediated by both the alpha and beta subunits.
CC       {ECO:0000250|UniProtKB:U5T880}.
CC   -!- MISCELLANEOUS: The light-harvesting system in Cryptophytes contains
CC       phycobiliprotein complexes. Unusually they are composed of either
CC       phycoerythrin (CPE) or phycocyanin (CPC) but never allophycocyanin
CC       (APC), with only one type of biliprotein being present in any one
CC       species. Unlike cyanobacteria or red algae these proteins are not
CC       arranged into higher-order phycobilisome complexes, and they are found
CC       in the thylakoid lumen.
CC   -!- SIMILARITY: Belongs to the phycoerythrin family. {ECO:0000305}.
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DR   PIR; S10602; S10602.
DR   AlphaFoldDB; P23815; -.
DR   SMR; P23815; -.
DR   GO; GO:0009535; C:chloroplast thylakoid membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0030089; C:phycobilisome; IEA:InterPro.
DR   GO; GO:0015979; P:photosynthesis; IEA:UniProtKB-KW.
DR   Gene3D; 3.90.510.10; -; 1.
DR   InterPro; IPR011070; Globular_prot_asu/bsu.
DR   InterPro; IPR037011; Phycoerythr-like_a_sf.
DR   InterPro; IPR004228; Phycoerythr_a.
DR   Pfam; PF02972; Phycoerythr_ab; 1.
DR   SUPFAM; SSF56568; SSF56568; 1.
PE   1: Evidence at protein level;
KW   Bile pigment; Chloroplast; Chromophore; Direct protein sequencing;
KW   Electron transport; Membrane; Photosynthesis; Plastid; Thylakoid;
KW   Transport.
FT   CHAIN           1..70
FT                   /note="Phycocyanin-645 alpha-2 chain"
FT                   /id="PRO_0000199210"
FT   BINDING         16
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000250|UniProtKB:U5T880"
FT   BINDING         18
FT                   /ligand="mesobiliverdin"
FT                   /ligand_id="ChEBI:CHEBI:189061"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /note="covalent"
FT                   /evidence="ECO:0000250|UniProtKB:U5T880"
FT   BINDING         26
FT                   /ligand="mesobiliverdin"
FT                   /ligand_id="ChEBI:CHEBI:189061"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000250|UniProtKB:U5T880"
FT   BINDING         41
FT                   /ligand="mesobiliverdin"
FT                   /ligand_id="ChEBI:CHEBI:189061"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000250|UniProtKB:U5T880"
SQ   SEQUENCE   70 AA;  7533 MW;  46260B302F898813 CRC64;
     KNGDLRTPVI TIFDARGCKD HANKEYTGPK AGGADDEMCV KVAMQKIAVA EDAAALVLKE
     CLSELKARKK