Disease relevance of RBP4

• Functional expression of the uncomplexed serum retinol-binding protein in Escherichia coli. Ligand binding and reversible unfolding characteristics [1].
• Concentrations of retinol and RBP increased 7- to 8-fold (P less than 0.01) in flushings where filamentous conceptuses were present [2].
• Interactions amongst plasma retinol-binding protein, transthyretin and their ligands: implications in vitamin A homeostasis and transthyretin amyloidosis [3].

High impact information on RBP4

• Homology of beta-lactoglobulin, serum retinol-binding protein, and protein HC [4].
• Fractional synthesis rates of retinol-binding protein, transthyretin, and a new peptide measured by stable isotope techniques in neonatal pigs [5].
• Western blotting procedures employing an antiserum raised against the most basic isoforms showed that the amount of retinol-binding protein in uterine secretions increased markedly in ovariectomized animals in response to long term progesterone treatment [6].
• RESULTS: Plasma retinol levels in patients receiving HAART were decreased in comparison with those not receiving antiretroviral drugs (51 +/- 5 versus 66 +/- 11 microg/dl; P = 0.03), whereas retinol-binding protein levels were increased (68 +/- 18 versus 45 +/- 10 mg/l; P = 0.04) [7].
• Secretion of large quantities of RBP by the trophoblast of preimplantation pig conceptuses suggests important roles for vitamin A and RBP near the time of conceptus elongation [8].

Chemical compound and disease context of RBP4

• Recovered flushings were analysed for total luminal protein, retinol binding protein, uteroferrin, prostaglandin E and prostaglandin F [9].
• Neither estrone nor estradiol affected total protein or AP and estrone treatment decreased (P < .05) RBP in uterine flushings from PP gilts [10].

Biological context of RBP4

• Investigation of the retinol-binding protein 4 (RBP4) gene as a candidate gene for increased litter size in pigs [11].
• Three diallelic RFLP markers at candidate gene loci for litter size, the estrogen receptor (ESR) gene, the prolactin receptor (PRLR) gene, and the retinol-binding protein 4 (RBP4) gene, were evaluated for their association with the number of piglets born alive in different German pig lines [12].
• After adjustment for effects of genetic drift, frequency of the two alleles segregating for the FS and RBP4 loci did not differ significantly between lines [13].
• Porcine conceptus RBP and human serum RBP share 91% amino acid sequence identity [8].
• Using an oligonucleotide probe corresponding to a highly conserved region of all known mammalian RBP, we have isolated an apparently full-length cDNA clone for porcine conceptus RBP from a cDNA library constructed from pig conceptuses collected between days 13-17 of pregnancy [8].

Anatomical context of RBP4

• The retinol-binding protein of the expanding pig blastocyst: molecular cloning and expression in trophectoderm and embryonic disc [8].
• Finally, RBP mRNA was examined in the uterine endometrium of mature gilts on day 13 of the estrous cycle (n = 4), day 13 of pseudopregnancy (2.5 mg EB given on days 11-12; n = 4), or day 13 of pregnancy after conceptuses had elongated (n = 4) [2].
• Steroid regulation of the synthesis and secretion of retinol-binding protein by the uterus of the pig [2].
• In these structures, immunoreactive RBP was localized, as was cellular retinoic acid-binding protein I. Retinoid X receptor beta was observed in the nucleus of myometrium and endometrium [14].
• The association of RBP and TF concentrations with AP in various maternal and conceptus compartments during pregnancy is consistent with the hypothesis that one function of these two proteins may be to protect maternal and fetal tissues from lipid peroxidation that is a possible consequence of iron transport via endometrial secretion of UF [15].

Associations of RBP4 with chemical compounds

• Guanidinium chloride-induced unfolding and refolding experiments suggest that the recombinant retinol-binding protein adopts a stable conformation despite being expressed and purified in the absence of the large hydrophobic ligand [1].
• The objective of this study was to determine how conceptus-derived estrogen might modulate this production of RBP around days 11-13 of pregnancy when conceptuses elongate from spheres to long thread-like forms [2].
• Detection of transcripts for retinoic acid receptors, retinol-binding protein, and transforming growth factors during rapid trophoblastic elongation in the porcine conceptus [16].
• Together these findings suggest that 1) the areolar gland subunits are important for transport of retinol and retinol-RBP, and 2) retinoid binding proteins are involved in the development and growth of the porcine placenta [17].
• Of the various major proteins, clusterin, glutathione peroxidase, retinol-binding protein, lactoferrin, EP4, beta-N-acetyl-hexosaminidase, alpha-mannosidase, and procathepsin L were identified and localized along the organ [18].

Other interactions of RBP4

• Characterization of a line of pigs previously selected for increased litter size for RBP4 and follistatin [13].
• Uteroferrin induces lipid peroxidation in endometrial and conceptus microsomal membranes and is inhibited by apotransferrin, retinol binding protein, and the uteroferrin-associated proteins [19].
• It bound thyroxine, retinol-binding protein, anti-(rat transthyretin) antibodies and behaved similarly to transthyretins from other vertebrate species when plasma was extracted with phenol [20].
• For treatments 7 through 10, membranes were preincubated (0 degrees C, 3 h) with either 7) no treatment, 8) 50 microM fetuin, 9) 50 microM holoretinol binding protein (holoRBP: retinol binding protein [HoloRBP] with retinol bound), or 10) 50 microM apoRBP (RBP with no retinol bound) followed by incubation with 50 microM ASC + 100 microM UF [19].
• Association between uteroferrin, retinol-binding protein, and transferrin within the uterine and conceptus compartments during pregnancy in swine [15].

Analytical, diagnostic and therapeutic context of RBP4

• Western blot analysis of conceptus culture medium demonstrated that the conceptuses of cattle (on day 19) and sheep (on day 15) as well as pigs secrete RBP during early pregnancy [8].
• RBP mRNA was detectable within the trophoblast of day 11 porcine conceptuses by in situ hybridization with a 618-basepair 35S-labeled probe corresponding to the 3' end of porcine RBP [8].
• Northern blot analysis with a cDNA representing uterine RBP revealed a single endometrial mRNA 1.1 kilobases in length [2].
• Three proteins involved in 1) serum transport of retinol (retinol binding protein [RBP]), 2) cellular transport and metabolism of retinol (cellular RBP [CRBP] I), and 3) retinoic acid (cellular retinoic acid binding protein [CRABP] I), respectively, have been located by immunohistochemistry during gestation in the porcine placenta [17].
• Immunoprecipitation demonstrated that the secretion of immunoreactive RBP increased by day 3 [21].

References