ID   CRYAA_LITCT             Reviewed;         173 AA.
AC   Q91311;
DT   15-JUL-1999, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   03-AUG-2022, entry version 78.
DE   RecName: Full=Alpha-crystallin A chain;
GN   Name=CRYAA;
OS   Lithobates catesbeianus (American bullfrog) (Rana catesbeiana).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Amphibia;
OC   Batrachia; Anura; Neobatrachia; Ranoidea; Ranidae; Lithobates.
OX   NCBI_TaxID=8400;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RX   PubMed=7763271; DOI=10.1006/bbrc.1995.1752;
RA   Lu S.F., Pan F.M., Chiou S.H.;
RT   "Sequence analysis of frog alpha-crystallin cDNA and its deduced primary
RT   structure: comparison of alpha A subunit chains among different vertebrate
RT   species.";
RL   Biochem. Biophys. Res. Commun. 210:974-981(1995).
CC   -!- FUNCTION: Contributes to the transparency and refractive index of the
CC       lens. May act as a chaperone, preventing aggregation of various
CC       proteins under a wide range of stress conditions.
CC       {ECO:0000250|UniProtKB:P02489}.
CC   -!- SUBUNIT: Heteropolymer composed of three CRYAA and one CRYAB subunits
CC       (By similarity). Inter-subunit bridging via zinc ions enhances
CC       stability, which is crucial as there is no protein turn over in the
CC       lens. Can also form homodimers and homotetramers (dimers of dimers)
CC       which serve as the building blocks of homooligomers (By similarity).
CC       Within homooligomers, the zinc-binding motif is created from residues
CC       of 3 different molecules. His-100 and Glu-102 from one molecule are
CC       ligands of the zinc ion, and His-107 and His-154 residues from
CC       additional molecules complete the site with tetrahedral coordination
CC       geometry (By similarity). {ECO:0000250|UniProtKB:P02470,
CC       ECO:0000250|UniProtKB:P02489}.
CC   -!- SUBCELLULAR LOCATION: Cytoplasm {ECO:0000250|UniProtKB:P02489}. Nucleus
CC       {ECO:0000250|UniProtKB:P02489}. Note=Translocates to the nucleus during
CC       heat shock. {ECO:0000250|UniProtKB:P02489}.
CC   -!- SIMILARITY: Belongs to the small heat shock protein (HSP20) family.
CC       {ECO:0000255|PROSITE-ProRule:PRU00285}.
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DR   EMBL; X85205; CAA59471.1; -; mRNA.
DR   PIR; JC4148; JC4148.
DR   AlphaFoldDB; Q91311; -.
DR   SMR; Q91311; -.
DR   GO; GO:0005737; C:cytoplasm; IEA:UniProtKB-SubCell.
DR   GO; GO:0005634; C:nucleus; IEA:UniProtKB-SubCell.
DR   GO; GO:0046872; F:metal ion binding; IEA:UniProtKB-KW.
DR   GO; GO:0005212; F:structural constituent of eye lens; IEA:UniProtKB-KW.
DR   Gene3D; 2.60.40.790; -; 1.
DR   InterPro; IPR002068; A-crystallin/Hsp20_dom.
DR   InterPro; IPR001436; Alpha-crystallin/sHSP_animal.
DR   InterPro; IPR012274; Alpha-crystallin_A.
DR   InterPro; IPR003090; Alpha-crystallin_N.
DR   InterPro; IPR008978; HSP20-like_chaperone.
DR   PANTHER; PTHR45640; PTHR45640; 1.
DR   PANTHER; PTHR45640:SF14; PTHR45640:SF14; 1.
DR   Pfam; PF00525; Crystallin; 1.
DR   Pfam; PF00011; HSP20; 1.
DR   PIRSF; PIRSF036514; Sm_HSP_B1; 1.
DR   PRINTS; PR00299; ACRYSTALLIN.
DR   SUPFAM; SSF49764; SSF49764; 1.
DR   PROSITE; PS01031; SHSP; 1.
PE   2: Evidence at transcript level;
KW   Acetylation; Cytoplasm; Eye lens protein; Metal-binding; Nucleus; Zinc.
FT   CHAIN           1..173
FT                   /note="Alpha-crystallin A chain"
FT                   /id="PRO_0000125900"
FT   DOMAIN          52..162
FT                   /note="sHSP"
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00285"
FT   REGION          146..173
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   BINDING         100
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000250|UniProtKB:P02470"
FT   BINDING         102
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_label="1"
FT                   /evidence="ECO:0000250|UniProtKB:P02470"
FT   BINDING         107
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_label="2"
FT                   /evidence="ECO:0000250|UniProtKB:P02470"
FT   BINDING         154
FT                   /ligand="Zn(2+)"
FT                   /ligand_id="ChEBI:CHEBI:29105"
FT                   /ligand_label="3"
FT                   /evidence="ECO:0000250|UniProtKB:P02470"
FT   MOD_RES         1
FT                   /note="N-acetylmethionine"
FT                   /evidence="ECO:0000250"
SQ   SEQUENCE   173 AA;  19899 MW;  31B9BD2770ABC290 CRC64;
     MDIAIQHPWF KRALGPFYPN RLFDQVFGEG MFDYDLFPFL SSTVSPYYRH SLFRGFMDSG
     ISEVRSDRDR FTINLDVKHF SPDDLTVKIL DDFVEIHGKH SERQDDHGYI SREFHRRYRL
     PSNLDQSSIS CSLSADGILT FSGPKMMSGL DSSHSERPIP VSREEKPTSA PSS