ID   B2MG_ACIBE              Reviewed;         122 AA.
AC   Q9PRF8; Q9PVL3; Q9PVL4; Q9PVL5;
DT   30-MAY-2003, integrated into UniProtKB/Swiss-Prot.
DT   01-MAY-2000, sequence version 1.
DT   25-MAY-2022, entry version 68.
DE   RecName: Full=Beta-2-microglobulin;
DE   Flags: Precursor;
GN   Name=b2m;
OS   Acipenser baerii (Siberian sturgeon).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi;
OC   Actinopterygii; Chondrostei; Acipenseriformes; Acipenseridae; Acipenser.
OX   NCBI_TaxID=27689;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [GENOMIC DNA / MRNA].
RC   TISSUE=Spleen;
RX   PubMed=10541811; DOI=10.1007/s002510050690;
RA   Lundqvist M.L., Appelkvist P., Hermsen T., Pilstroem L., Stet R.J.M.;
RT   "Characterisation of beta2-microglubulin in a primitive fish the Siberian
RT   sturgeon (Acipenser baeri).";
RL   Immunogenetics 50:79-83(1999).
CC   -!- FUNCTION: Component of the class I major histocompatibility complex
CC       (MHC). Involved in the presentation of peptide antigens to the immune
CC       system (By similarity). {ECO:0000250}.
CC   -!- SUBUNIT: Heterodimer of an alpha chain and a beta chain. Beta-2-
CC       microglobulin is the beta-chain of major histocompatibility complex
CC       class I molecules (By similarity). {ECO:0000250}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250}.
CC   -!- SIMILARITY: Belongs to the beta-2-microglobulin family. {ECO:0000305}.
CC   ---------------------------------------------------------------------------
CC   Copyrighted by the UniProt Consortium, see https://www.uniprot.org/terms
CC   Distributed under the Creative Commons Attribution (CC BY 4.0) License
CC   ---------------------------------------------------------------------------
DR   EMBL; AJ132766; CAB61322.1; -; mRNA.
DR   EMBL; AJ133652; CAB61323.1; -; Genomic_DNA.
DR   EMBL; AJ133653; CAB61324.1; -; Genomic_DNA.
DR   EMBL; AJ133654; CAB61325.1; -; Genomic_DNA.
DR   EMBL; AJ133655; CAB61326.1; -; Genomic_DNA.
DR   AlphaFoldDB; Q9PRF8; -.
DR   SMR; Q9PRF8; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   GO; GO:0042612; C:MHC class I protein complex; IEA:UniProtKB-KW.
DR   GO; GO:0002474; P:antigen processing and presentation of peptide antigen via MHC class I; IEA:UniProtKB-KW.
DR   GO; GO:0006955; P:immune response; IEA:InterPro.
DR   Gene3D; 2.60.40.10; -; 1.
DR   InterPro; IPR015707; B2Microglobulin.
DR   InterPro; IPR007110; Ig-like_dom.
DR   InterPro; IPR036179; Ig-like_dom_sf.
DR   InterPro; IPR013783; Ig-like_fold.
DR   InterPro; IPR003006; Ig/MHC_CS.
DR   InterPro; IPR003597; Ig_C1-set.
DR   PANTHER; PTHR19944:SF62; PTHR19944:SF62; 1.
DR   Pfam; PF07654; C1-set; 1.
DR   SMART; SM00407; IGc1; 1.
DR   SUPFAM; SSF48726; SSF48726; 1.
DR   PROSITE; PS50835; IG_LIKE; 1.
DR   PROSITE; PS00290; IG_MHC; 1.
PE   2: Evidence at transcript level;
KW   Disulfide bond; Immunity; Immunoglobulin domain; MHC I; Secreted; Signal.
FT   SIGNAL          1..23
FT                   /evidence="ECO:0000255"
FT   CHAIN           24..122
FT                   /note="Beta-2-microglobulin"
FT                   /id="PRO_0000018805"
FT   DOMAIN          28..117
FT                   /note="Ig-like C1-type"
FT   DISULFID        48..103
FT                   /evidence="ECO:0000255|PROSITE-ProRule:PRU00114"
FT   VARIANT         3
FT                   /note="L -> R (in a1)"
FT   VARIANT         54
FT                   /note="H -> Q (in b1)"
FT   VARIANT         112..115
FT                   /note="EATR -> GAKS (in b1 and b2)"
SQ   SEQUENCE   122 AA;  13752 MW;  F3C85D0C280E8E4A CRC64;
     MFLRSTFVAA LVACLAYIHL GDATEAMPKV QIYSRNVGEL GKPNTLICHV SGFHPPNIKL
     QLLKNDVEIE GAQQSDLAFH QGWHFHLTKS VAFTPKEGEH YSCKVEHSTL REATRFTWTP
     DM