ID   PHEA2_HEMVI             Reviewed;         109 AA.
AC   C0HM12; A0A075B5G1; A0A075BTU2;
DT   25-MAY-2022, integrated into UniProtKB/Swiss-Prot.
DT   25-MAY-2022, sequence version 1.
DT   03-AUG-2022, entry version 2.
DE   RecName: Full=Phycoerythrin alpha-2 subunit {ECO:0000305};
GN   Name=cpeA2 {ECO:0000312|EMBL:AGR45602.1};
OS   Hemiselmis virescens.
OG   Plastid; Chloroplast {ECO:0000305}.
OC   Eukaryota; Cryptophyceae; Cryptomonadales; Hemiselmidaceae; Hemiselmis.
OX   NCBI_TaxID=77927;
RN   [1] {ECO:0000312|EMBL:AGR45602.1}
RP   NUCLEOTIDE SEQUENCE [MRNA], X-RAY CRYSTALLOGRAPHY (1.70 ANGSTROMS) OF
RP   48-109 IN COMPLEX WITH PHYCOCYANOBILIN, AND SUBUNIT.
RC   STRAIN=M1635 {ECO:0000312|EMBL:AGR45602.1};
RX   PubMed=24979784; DOI=10.1073/pnas.1402538111;
RA   Harrop S.J., Wilk K.E., Dinshaw R., Collini E., Mirkovic T., Teng C.Y.,
RA   Oblinsky D.G., Green B.R., Hoef-Emden K., Hiller R.G., Scholes G.D.,
RA   Curmi P.M.;
RT   "Single-residue insertion switches the quaternary structure and exciton
RT   states of cryptophyte light-harvesting proteins.";
RL   Proc. Natl. Acad. Sci. U.S.A. 111:E2666-E2675(2014).
CC   -!- FUNCTION: Light-harvesting photosynthetic tetrapyrrole chromophore-
CC       protein from the phycobiliprotein complex. {ECO:0000305}.
CC   -!- SUBUNIT: Heterotetramer of 2 identical alpha chains and 2 identical
CC       beta chains which form 2 alpha-beta heterodimers within the
CC       heterotetramer. The two alpha-beta heterodimers are rotated to an open
CC       configuration in contrast to the closed configuration found in other
CC       cryptophyte species due to the insertion of a single amino acid, Asp-
CC       65, in a conserved region of the alpha chain. In the open form, the
CC       central chromophores are not in physical contact but are separated by a
CC       water-filled channel. {ECO:0000269|PubMed:24979784}.
CC   -!- SUBCELLULAR LOCATION: Plastid, chloroplast thylakoid membrane
CC       {ECO:0000305}; Peripheral membrane protein {ECO:0000305}; Lumenal side
CC       {ECO:0000305}.
CC   -!- PTM: Contains three phycocyanobilin chromophores with binding mediated
CC       by both the alpha and beta subunits. {ECO:0000269|PubMed:24979784}.
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. {ECO:0000305}.
CC   -!- SIMILARITY: Belongs to the phycoerythrin family. {ECO:0000305}.
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DR   EMBL; KC905457; AGR45602.1; -; mRNA.
DR   PDB; 4LM6; X-ray; 1.70 A; A/C=48-109.
DR   PDBsum; 4LM6; -.
DR   GO; GO:0009535; C:chloroplast thylakoid membrane; IEA:UniProtKB-SubCell.
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   SUPFAM; SSF56568; SSF56568; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Bile pigment; Chloroplast; Chromophore; Electron transport;
KW   Membrane; Photosynthesis; Plastid; Thylakoid; Transport.
FT   CHAIN           1..109
FT                   /note="Phycoerythrin alpha-2 subunit"
FT                   /id="PRO_0000455545"
FT   BINDING         6
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /ligand_label="1"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000269|PubMed:24979784,
FT                   ECO:0007744|PDB:4LM6"
FT   BINDING         16
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /ligand_label="3"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000269|PubMed:24979784,
FT                   ECO:0007744|PDB:4LM6"
FT   BINDING         17
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /ligand_label="2"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000269|PubMed:24979784,
FT                   ECO:0007744|PDB:4LM6"
FT   BINDING         20
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /ligand_label="3"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /note="covalent"
FT                   /evidence="ECO:0000269|PubMed:24979784,
FT                   ECO:0007744|PDB:4LM6"
FT   BINDING         27
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /ligand_label="3"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000269|PubMed:24979784,
FT                   ECO:0007744|PDB:4LM6"
FT   BINDING         28
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /ligand_label="3"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000269|PubMed:24979784,
FT                   ECO:0007744|PDB:4LM6"
FT   BINDING         39
FT                   /ligand="(2R,3E)-phycocyanobilin"
FT                   /ligand_id="ChEBI:CHEBI:85275"
FT                   /ligand_label="3"
FT                   /ligand_note="ligand shared with beta subunit"
FT                   /evidence="ECO:0000269|PubMed:24979784,
FT                   ECO:0007744|PDB:4LM6"
SQ   SEQUENCE   109 AA;  11173 MW;  B0328C6DFD868087 CRC64;
     MYTKAVLLAF VGSAAAFNAP MMTVRRDAIA TGAAAAVVAP LLRPAGAKMA TDSKAPLIEL
     FDERDGCKGP AANKASDVGE PGLCVKVSMQ KVAMNAAAAK SVATNYMRK