ID   CASB_EQUAS              Reviewed;         226 AA.
AC   P86273;
DT   26-MAY-2009, integrated into UniProtKB/Swiss-Prot.
DT   26-MAY-2009, sequence version 1.
DT   25-MAY-2022, entry version 19.
DE   RecName: Full=Beta-casein {ECO:0000303|PubMed:19462407};
GN   Name=CSN2 {ECO:0000250|UniProtKB:P02666};
OS   Equus asinus (Donkey) (Equus africanus asinus).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Perissodactyla; Equidae; Equus.
OX   NCBI_TaxID=9793;
RN   [1]
RP   PROTEIN SEQUENCE, MASS SPECTROMETRY, PHOSPHORYLATION, AND VARIANT A-DELTA5
RP   27-GLU--LYS-34 DEL.
RC   TISSUE=Milk;
RX   PubMed=19462407; DOI=10.1002/rcm.4087;
RA   Cunsolo V., Cairone E., Saletti R., Muccilli V., Foti S.;
RT   "Sequence and phosphorylation level determination of two donkey beta-
RT   caseins by mass spectrometry.";
RL   Rapid Commun. Mass Spectrom. 23:1907-1916(2009).
CC   -!- FUNCTION: Important role in determination of the surface properties of
CC       the casein micelles. {ECO:0000250|UniProtKB:P02666}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000305}.
CC   -!- TISSUE SPECIFICITY: Mammary gland specific. Secreted in milk.
CC       {ECO:0000305}.
CC   -!- PTM: There are at least three different forms found in milk, with
CC       varying degrees of phosphorylation. These include form 5-P which is
CC       phosphorylated at three sites, this form is present in low amounts,
CC       form 6-P which is phosphorylated at six sites, and form 7-P which is
CC       phosphorylated at seven sites. {ECO:0000269|PubMed:19462407}.
CC   -!- MASS SPECTROMETRY: Mass=25529; Mass_error=2; Method=MALDI;
CC       Evidence={ECO:0000269|PubMed:19462407};
CC   -!- MASS SPECTROMETRY: Mass=24606; Mass_error=2; Method=MALDI; Note=Variant
CC       A-Delta5.; Evidence={ECO:0000269|PubMed:19462407};
CC   -!- SIMILARITY: Belongs to the beta-casein family. {ECO:0000255}.
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DR   AlphaFoldDB; P86273; -.
DR   SMR; P86273; -.
DR   GO; GO:0005576; C:extracellular region; IEA:UniProtKB-SubCell.
DR   InterPro; IPR001588; Casein.
DR   InterPro; IPR016345; Casein_beta.
DR   PANTHER; PTHR11500; PTHR11500; 1.
DR   Pfam; PF00363; Casein; 1.
DR   PIRSF; PIRSF002372; Beta-casein; 1.
PE   1: Evidence at protein level;
KW   Direct protein sequencing; Milk protein; Phosphoprotein; Secreted.
FT   CHAIN           1..226
FT                   /note="Beta-casein"
FT                   /id="PRO_0000376023"
FT   REGION          1..51
FT                   /note="Disordered"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        10..26
FT                   /note="Polar residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   COMPBIAS        27..51
FT                   /note="Basic and acidic residues"
FT                   /evidence="ECO:0000256|SAM:MobiDB-lite"
FT   MOD_RES         9
FT                   /note="Phosphoserine"
FT                   /evidence="ECO:0000250|UniProtKB:Q9GKK3"
FT   MOD_RES         12
FT                   /note="Phosphothreonine"
FT                   /evidence="ECO:0000250|UniProtKB:Q9GKK3"
FT   MOD_RES         15
FT                   /note="Phosphoserine"
FT                   /evidence="ECO:0000250|UniProtKB:P05814"
FT   MOD_RES         17
FT                   /note="Phosphoserine"
FT                   /evidence="ECO:0000250|UniProtKB:P05814"
FT   MOD_RES         18
FT                   /note="Phosphoserine"
FT                   /evidence="ECO:0000250|UniProtKB:P05814"
FT   MOD_RES         25
FT                   /note="Phosphoserine"
FT                   /evidence="ECO:0000250|UniProtKB:P05814"
FT   VARIANT         27..34
FT                   /note="Missing (in A-Delta5)"
FT                   /evidence="ECO:0000269|PubMed:19462407"
SQ   SEQUENCE   226 AA;  25529 MW;  46C7EBE8C9743BB0 CRC64;
     REKEELNVSS ETVESLSSNE PDSSSEESIT HINKEKSQKF KHEGQQQREV EHQDKISRFV
     QPQPVVYPYA EPVPYAVVPQ NILVLAQPPI VPFLQPEIME VSQAKETILP KRKVMPFLKS
     PIVPFSERQI LNPTNGENLR LPVHLIQPFM HQVPQSLLQT LMLPSQPVLS PPQSKVAPFP
     QPVVPYPQRD TPVQAFLLYQ DPQLGLTGEF DPATQPIVPV HNPVIV