ID   RET4_HORSE              Reviewed;         201 AA.
AC   Q28369;
DT   03-APR-2002, integrated into UniProtKB/Swiss-Prot.
DT   01-NOV-1996, sequence version 1.
DT   03-AUG-2022, entry version 111.
DE   RecName: Full=Retinol-binding protein 4;
DE   AltName: Full=Plasma retinol-binding protein;
DE            Short=PRBP;
DE            Short=RBP;
DE   Flags: Precursor;
GN   Name=RBP4;
OS   Equus caballus (Horse).
OC   Eukaryota; Metazoa; Chordata; Craniata; Vertebrata; Euteleostomi; Mammalia;
OC   Eutheria; Laurasiatheria; Perissodactyla; Equidae; Equus.
OX   NCBI_TaxID=9796;
RN   [1]
RP   NUCLEOTIDE SEQUENCE [MRNA].
RC   TISSUE=Endometrium;
RX   PubMed=7536053; DOI=10.1095/biolreprod52.2.438;
RA   McDowell K.J., Adams M.H., Franklin K.M., Baker C.B.;
RT   "Changes in equine endometrial retinol-binding protein RNA during the
RT   estrous cycle and early pregnancy and with exogenous steroids.";
RL   Biol. Reprod. 52:438-443(1995).
CC   -!- FUNCTION: Retinol-binding protein that mediates retinol transport in
CC       blood plasma. Delivers retinol from the liver stores to the peripheral
CC       tissues. Transfers the bound all-trans retinol to STRA6, that then
CC       facilitates retinol transport across the cell membrane.
CC       {ECO:0000250|UniProtKB:P02753}.
CC   -!- SUBUNIT: Interacts with TTR. Interaction with TTR prevents its loss by
CC       filtration through the kidney glomeruli. Interacts with STRA6.
CC       {ECO:0000250|UniProtKB:P02753}.
CC   -!- SUBCELLULAR LOCATION: Secreted {ECO:0000250|UniProtKB:P02753}.
CC   -!- SIMILARITY: Belongs to the calycin superfamily. Lipocalin family.
CC       {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; U21208; AAC48461.1; -; mRNA.
DR   PIR; I46257; I46257.
DR   RefSeq; NP_001075420.1; NM_001081951.1.
DR   AlphaFoldDB; Q28369; -.
DR   SMR; Q28369; -.
DR   STRING; 9796.ENSECAP00000049551; -.
DR   PaxDb; Q28369; -.
DR   PeptideAtlas; Q28369; -.
DR   PRIDE; Q28369; -.
DR   GeneID; 100049790; -.
DR   KEGG; ecb:100049790; -.
DR   CTD; 5950; -.
DR   InParanoid; Q28369; -.
DR   OrthoDB; 1631943at2759; -.
DR   Proteomes; UP000002281; Unplaced.
DR   GO; GO:0005615; C:extracellular space; ISS:UniProtKB.
DR   GO; GO:0016918; F:retinal binding; IEA:UniProtKB-KW.
DR   GO; GO:0019841; F:retinol binding; IBA:GO_Central.
DR   GO; GO:0034632; F:retinol transmembrane transporter activity; IEA:InterPro.
DR   GO; GO:0034633; P:retinol transport; IBA:GO_Central.
DR   Gene3D; 2.40.128.20; -; 1.
DR   InterPro; IPR012674; Calycin.
DR   InterPro; IPR022271; Lipocalin_ApoD.
DR   InterPro; IPR022272; Lipocalin_CS.
DR   InterPro; IPR000566; Lipocln_cytosolic_FA-bd_dom.
DR   InterPro; IPR002449; Retinol-bd/Purpurin.
DR   PANTHER; PTHR11873; PTHR11873; 1.
DR   Pfam; PF00061; Lipocalin; 1.
DR   PIRSF; PIRSF036893; Lipocalin_ApoD; 1.
DR   PIRSF; PIRSF500204; RBP_purpurin; 1.
DR   PRINTS; PR01174; RETINOLBNDNG.
DR   SUPFAM; SSF50814; SSF50814; 1.
DR   PROSITE; PS00213; LIPOCALIN; 1.
PE   2: Evidence at transcript level;
KW   Disulfide bond; Methylation; Reference proteome; Retinol-binding; Secreted;
KW   Signal; Transport; Vitamin A.
FT   SIGNAL          1..18
FT                   /evidence="ECO:0000250|UniProtKB:P02753"
FT   CHAIN           19..201
FT                   /note="Retinol-binding protein 4"
FT                   /id="PRO_0000017960"
FT   BINDING         116
FT                   /ligand="substrate"
FT                   /evidence="ECO:0000250|UniProtKB:P27485"
FT   MOD_RES         139
FT                   /note="Omega-N-methylarginine"
FT                   /evidence="ECO:0000250|UniProtKB:Q00724"
FT   DISULFID        22..178
FT                   /evidence="ECO:0000250|UniProtKB:P02753"
FT   DISULFID        88..192
FT                   /evidence="ECO:0000250|UniProtKB:P02753"
FT   DISULFID        138..147
FT                   /evidence="ECO:0000250|UniProtKB:P02753"
SQ   SEQUENCE   201 AA;  23022 MW;  12CF80834E4262DC CRC64;
     MEWVWALVVL AALGSAGAER DCRVSSFRVK ENFDKARFSG TWYAMAKKDP EGLFLQDNIV
     AEFSVDEYGQ MSATAKGRVR LLNNWDVCAD MVGTFTDTED PAKFKMKYWG VASFLQKGND
     DHWIIDTDYD TYAVQYSCRL LNLDGTCADS YSFVFARDPN GFPPEVQRIV RRRQEELCLA
     RQYRLISHNG YCDGKSDRNL L