ID   PHCA_CYACA              Reviewed;         162 AA.
AC   O19910;
DT   29-AUG-2001, integrated into UniProtKB/Swiss-Prot.
DT   01-JAN-1998, sequence version 1.
DT   03-AUG-2022, entry version 86.
DE   RecName: Full=C-phycocyanin alpha subunit;
GN   Name=cpcA;
OS   Cyanidium caldarium (Red alga).
OG   Plastid; Chloroplast.
OC   Eukaryota; Rhodophyta; Bangiophyceae; Cyanidiales; Cyanidiaceae; Cyanidium.
OX   NCBI_TaxID=2771;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [LARGE SCALE GENOMIC DNA].
RC   STRAIN=RK-1;
RX   PubMed=11040290; DOI=10.1007/s002390010101;
RA   Gloeckner G., Rosenthal A., Valentin K.-U.;
RT   "The structure and gene repertoire of an ancient red algal plastid
RT   genome.";
RL   J. Mol. Evol. 51:382-390(2000).
CC   -!- FUNCTION: Light-harvesting photosynthetic bile pigment-protein from the
CC       phycobiliprotein complex (phycobilisome, PBS). Phycocyanin is the major
CC       phycobiliprotein in the PBS rod.
CC   -!- SUBUNIT: Heterodimer of an alpha and a beta subunit, which further
CC       assembles into trimers and the trimers into hexamers. The basic
CC       functional unit of phycobiliproteins is a ring-shaped hexamer formed
CC       from two back-to-back trimers contacting via the alpha chain subunits.
CC       The trimers are composed of alpha/beta subunit heterodimers arranged
CC       around a three-fold axis of symmetry. The phycoerythrins also contain a
CC       gamma subunit which is located in the center of the hexamer.
CC       {ECO:0000250|UniProtKB:P00306}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast thylakoid membrane
CC       {ECO:0000250}; Peripheral membrane protein {ECO:0000250}; Stromal side
CC       {ECO:0000250}. Note=Part of the phycobilisome rod. {ECO:0000250}.
CC   -!- PTM: Contains one covalently linked phycocyanobilin chromophore.
CC       {ECO:0000250|UniProtKB:P00306}.
CC   -!- MISCELLANEOUS: The light-harvesting antenna system in red algae and
CC       cyanobacteria is formed of phycobilisomes. These are composed of the
CC       phycobiliproteins phycoerythrin (CPE), phycocyanin (CPC) and
CC       allophycocyanin (APC). Cyanobacteria also contain phycoerythrocyanin
CC       (PCC). The phycobiliproteins all share the same subunit composition and
CC       organization with variations in the covalently bound open-chain
CC       tetrapyrrole chromophores. The phycobiliprotein complexes are arranged
CC       sequentially in antenna complexes linked by linker proteins with CPE at
CC       the periphery, CPC in the middle and APC at the core feeding to the
CC       photosynthetic reaction center.
CC   -!- SIMILARITY: Belongs to the phycobiliprotein family. {ECO:0000305}.
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DR   EMBL; AF022186; AAB82679.1; -; Genomic_DNA.
DR   PIR; T11978; T11978.
DR   RefSeq; NP_045082.1; NC_001840.1.
DR   PDB; 6Y3D; X-ray; 1.80 A; AAA/CCC/EEE/GGG/III/KKK=1-162.
DR   PDBsum; 6Y3D; -.
DR   AlphaFoldDB; O19910; -.
DR   SMR; O19910; -.
DR   GeneID; 800115; -.
DR   GO; GO:0009535; C:chloroplast thylakoid membrane; IEA:UniProtKB-SubCell.
DR   GO; GO:0030089; C:phycobilisome; IEA:UniProtKB-KW.
DR   GO; GO:0015979; P:photosynthesis; IEA:UniProtKB-KW.
DR   Gene3D; 1.10.490.20; -; 1.
DR   InterPro; IPR009050; Globin-like_sf.
DR   InterPro; IPR012128; Phycobilisome_asu/bsu.
DR   InterPro; IPR038719; Phycobilisome_asu/bsu_sf.
DR   InterPro; IPR006246; Phycocyanin_a.
DR   Pfam; PF00502; Phycobilisome; 1.
DR   PIRSF; PIRSF000081; Phycocyanin; 1.
DR   SUPFAM; SSF46458; SSF46458; 1.
DR   TIGRFAMs; TIGR01338; phycocy_alpha; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Antenna complex; Bile pigment; Chloroplast; Chromophore;
KW   Electron transport; Membrane; Photosynthesis; Phycobilisome; Plastid;
KW   Thylakoid; Transport.
FT   CHAIN           1..162
FT                   /note="C-phycocyanin alpha subunit"
FT                   /id="PRO_0000199120"
FT   BINDING         72..75
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /evidence="ECO:0000250"
FT   BINDING         83..87
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /evidence="ECO:0000250"
FT   BINDING         84
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /note="covalent, via 1 link"
FT                   /evidence="ECO:0000250|UniProtKB:P00306"
FT   BINDING         128
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   162 AA;  17245 MW;  01D3DDCB35720E73 CRC64;
     MKTPITEAIA TADSQGRFLS NTELQSCAGR FQRAGASLDA ARSLTANAQR LIDGAAQAVY
     SKFPYTTQMT GPCYASSAIG KAKCSRDIGY YLRMVTYCLV AGGTGPMDEY LVAGLEEINR
     TFDLSPSWYV EALKNIKASH GLSGAAASEA NAYINYAINS LS