ID   CRA2_HOMGA              Reviewed;         174 AA.
AC   P80007;
DT   01-MAY-1991, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-1991, sequence version 1.
DT   25-MAY-2022, entry version 116.
DE   RecName: Full=Crustacyanin-A2 subunit;
OS   Homarus gammarus (European lobster) (Homarus vulgaris).
OC   Eukaryota; Metazoa; Ecdysozoa; Arthropoda; Crustacea; Multicrustacea;
OC   Malacostraca; Eumalacostraca; Eucarida; Decapoda; Pleocyemata; Astacidea;
OC   Nephropoidea; Nephropidae; Homarus.
OX   NCBI_TaxID=6707;
RN   [1]
RP   PROTEIN SEQUENCE.
RX   PubMed=2026162; DOI=10.1111/j.1432-1033.1991.tb15925.x;
RA   Keen J.N., Caceres I., Eliopoulos E.E., Zagalsky P.F., Findlay J.B.C.;
RT   "Complete sequence and model for the A2 subunit of the carotenoid pigment
RT   complex, crustacyanin.";
RL   Eur. J. Biochem. 197:407-417(1991).
RN   [2]
RP   X-RAY CRYSTALLOGRAPHY (3.23 ANGSTROMS) OF HETERODIMER OF A1 AND A3 IN
RP   COMPLEX WITH ASTAXANTHIN, AND DISULFIDE BONDS.
RX   PubMed=12119396; DOI=10.1073/pnas.152088999;
RA   Cianci M., Rizkallah P.J., Olczak A., Raftery J., Chayen N.E.,
RA   Zagalsky P.F., Helliwell J.R.;
RT   "The molecular basis of the coloration mechanism in lobster shell: beta-
RT   crustacyanin at 3.2-A resolution.";
RL   Proc. Natl. Acad. Sci. U.S.A. 99:9795-9800(2002).
CC   -!- FUNCTION: Binds the carotenoid astaxanthin (AXT) which provides the
CC       blue coloration to the carapace of the lobster.
CC   -!- SUBUNIT: Oligomer; Can form dimers (beta-crustacyanin); or complexes of
CC       16 subunits (alpha-crustacyanin). There are five types of subunits: A1,
CC       A2, A3, C1 and C2. {ECO:0000269|PubMed:12119396}.
CC   -!- SUBCELLULAR LOCATION: Secreted, extracellular space.
CC   -!- TISSUE SPECIFICITY: Found in the carapace.
CC   -!- SIMILARITY: Belongs to the calycin superfamily. Lipocalin family.
CC       {ECO:0000305}.
CC   -!- WEB RESOURCE: Name=Protein Spotlight; Note=Squeeze me - Issue 26 of
CC       September 2002;
CC       URL="https://web.expasy.org/spotlight/back_issues/026";
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DR   PIR; S15391; S15391.
DR   PDB; 1GKA; X-ray; 3.23 A; B=1-174.
DR   PDBsum; 1GKA; -.
DR   AlphaFoldDB; P80007; -.
DR   SMR; P80007; -.
DR   MINT; P80007; -.
DR   EvolutionaryTrace; P80007; -.
DR   GO; GO:0005615; C:extracellular space; IEA:UniProtKB-SubCell.
DR   GO; GO:0031409; F:pigment binding; IEA:UniProtKB-KW.
DR   Gene3D; 2.40.128.20; -; 1.
DR   InterPro; IPR012674; Calycin.
DR   InterPro; IPR003057; Invtbrt_color.
DR   InterPro; IPR022271; Lipocalin_ApoD.
DR   InterPro; IPR022272; Lipocalin_CS.
DR   InterPro; IPR000566; Lipocln_cytosolic_FA-bd_dom.
DR   Pfam; PF00061; Lipocalin; 1.
DR   PIRSF; PIRSF036893; Lipocalin_ApoD; 1.
DR   PRINTS; PR01273; INVTBRTCOLOR.
DR   SUPFAM; SSF50814; SSF50814; 1.
DR   PROSITE; PS00213; LIPOCALIN; 1.
PE   1: Evidence at protein level;
KW   3D-structure; Direct protein sequencing; Disulfide bond; Pigment; Secreted;
KW   Transport.
FT   CHAIN           1..174
FT                   /note="Crustacyanin-A2 subunit"
FT                   /id="PRO_0000201010"
FT   DISULFID        12..119
FT                   /evidence="ECO:0000269|PubMed:12119396"
FT   DISULFID        46..170
FT                   /evidence="ECO:0000269|PubMed:12119396"
FT   STRAND          7..10
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   TURN            23..26
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          28..35
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          45..54
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   TURN            55..58
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          59..67
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          69..71
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          73..76
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          79..81
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          90..94
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          96..98
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          101..108
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          110..121
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          123..136
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   STRAND          139..141
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   HELIX           142..154
FT                   /evidence="ECO:0007829|PDB:1GKA"
FT   HELIX           158..160
FT                   /evidence="ECO:0007829|PDB:1GKA"
SQ   SEQUENCE   174 AA;  19670 MW;  AC47FAA650C5E44E CRC64;
     DGIPSFVTAG KCASVANQDN FDLRRYAGRW YQTHIIENAY QPVTRCIHSN YEYSTNDYGF
     KVTTAGFNPN DEYLKIDFKV YPTKEFPAAH MLIDAPSVFA APYEVIETDY ETYSCVYSCI
     TTDNYKSEFA FVFSRTPQTS GPAVEKTAAV FNKNGVEFSK FVPVSHTAEC VYRA