ID   PHCA_POLUR              Reviewed;         162 AA.
AC   P59858;
DT   26-SEP-2003, integrated into UniProtKB/Swiss-Prot.
DT   26-SEP-2003, sequence version 1.
DT   03-AUG-2022, entry version 76.
DE   RecName: Full=R-phycocyanin alpha chain;
GN   Name=rpcA;
OS   Polysiphonia urceolata (Red alga) (Conferva urceolata).
OG   Plastid; Chloroplast.
OC   Eukaryota; Rhodophyta; Florideophyceae; Rhodymeniophycidae; Ceramiales;
OC   Rhodomelaceae; Polysiphonioideae; Polysiphonia.
OX   NCBI_TaxID=65404;
RN   [1]
RP   X-RAY CRYSTALLOGRAPHY (2.4 ANGSTROMS) IN COMPLEX WITH RPCB AND
RP   PHYCOCYANOBILIN, FUNCTION, AND SUBUNIT.
RX   PubMed=11463658; DOI=10.1016/s0006-3495(01)75774-8;
RA   Jiang T., Zhang J.P., Chang W.R., Liang D.C.;
RT   "Crystal structure of R-phycocyanin and possible energy transfer pathways
RT   in the phycobilisome.";
RL   Biophys. J. 81:1171-1179(2001).
CC   -!- FUNCTION: Light-harvesting photosynthetic tetrapyrrole chromophore-
CC       protein from the phycobiliprotein complex (phycobilisome, PBS).
CC       Phycocyanin is the major phycobiliprotein in the PBS rod.
CC       {ECO:0000269|PubMed:11463658}.
CC   -!- SUBUNIT: Heterododecamer of 6 alpha and 6 beta chains. 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:0000269|PubMed:11463658}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast thylakoid membrane;
CC       Peripheral membrane protein; Stromal side. Note=Part of the
CC       phycobilisome rod.
CC   -!- PTM: Contains one covalently linked phycocyanobilin chromophore.
CC       {ECO:0000269|PubMed:11463658}.
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   PDB; 1F99; X-ray; 2.40 A; A/K/M=1-162.
DR   PDBsum; 1F99; -.
DR   AlphaFoldDB; P59858; -.
DR   SMR; P59858; -.
DR   EvolutionaryTrace; P59858; -.
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="R-phycocyanin alpha chain"
FT                   /id="PRO_0000199135"
FT   BINDING         83..87
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT   BINDING         84
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /note="covalent, via 1 link"
FT                   /evidence="ECO:0000269|PubMed:11463658"
FT   BINDING         115..124
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT   HELIX           4..14
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   HELIX           21..46
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   HELIX           48..62
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   HELIX           65..68
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   STRAND          74..77
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   HELIX           78..101
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   HELIX           105..110
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   TURN            111..114
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   HELIX           115..121
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   HELIX           126..139
FT                   /evidence="ECO:0007829|PDB:1F99"
FT   HELIX           144..161
FT                   /evidence="ECO:0007829|PDB:1F99"
SQ   SEQUENCE   162 AA;  17570 MW;  6DC32AE0BB371BA2 CRC64;
     MKTPLTEAIA AADSQGRFLS NTELQVVNGR YNRATSSLEA AKALTANADR LISGAANAVY
     SKFPYTTQMP GPNYSSTAIG KAKCARDIGY YLRMVTYCLV VGGTGPMDDY LVAGLEEINR
     TFELSPSWYI EALKYIKNNH GLSGDVANEA NTYIDYAINT LS