Retinol Binding Protein

RBP7 is a member of a superfamily of small cytoplasmic proteins which interact with hydrophobic ligands. RBP7 is cytoplasmic protein which, like CRBP I and CRBP II, forms ?-barrel structures and participates in the intracellular transport of retinol. RBP7 is a newly identified cellular retinol carrier, which is expressed in the kidney, heart and transverse colon in humans.

RBP5 is a member of the Retinol-binding proteins family. Estimation of retinol-binding protein is used to determine visceral protein mass in nutritional studies related to health. RBP5 has a higher expression in the adult kidney and liver and to a lesser extent in the adult and fetal spleen, adult lymph nodes and appendix, and fetal liver and kidney. RBP5 expression is strongly decreased in hepatocellular carcinoma tissues.

Retinol Binding Protein-4 or RBP4, is the retinol currier protein in the plasma. RBP4 takes part on the conversion of retinol to the stable and soluble retinol complex in the plasma. RBP4 carries retinol from the liver tissue where its store to peripheral tissues. RBP-retinol complex has interactions with transthyretin in the plasma, thus prevents its loss by filtration in the kidney.

Retinol binding protein 4(RBP4) belongs to the lipocalin family and is the specific carrier for retinol (vitamin A alcohol) in the blood. This protein was found to be expressed and secreted by adipose tissue, and was strongly associated with insulin resistance. It delivers retinol from the liver stores to the peripheral tissues. In plasma, the RBP-retinol complex interacts with transthyretin which prevents its loss by filtration through the kidney glomeruli.
RBP4 delivers retinol from the liver to the peripheral tissues. In plasma, the rbp-retinol complex interacts with transthyretin, this prevents its loss by filtration through the kidney glomeruli.

Retinol binding protein 4(RBP4) belongs to the lipocalin family and is the specific carrier for retinol (vitamin A alcohol) in the blood. This protein was found to be expressed and secreted by adipose tissue, and was strongly associated with insulin resistance. It delivers retinol from the liver stores to the peripheral tissues. In plasma, the RBP-retinol complex interacts with transthyretin which prevents its loss by filtration through the kidney glomeruli.
RBP4 delivers retinol from the liver to the peripheral tissues. In plasma, the rbp-retinol complex interacts with transthyretin, this prevents its loss by filtration through the kidney glomeruli.

Retinol-binding proteins (RBP) are a family of proteins with various functions. Retinol and retinoic acid play crucial roles in the modulation of gene expression and overall development of an embryo. However, deficit or excess of either one of these substances can cause early embryo mortality or developmental malformations. Regulation of transport and metabolism of retinol necessary for a successful pregnancy is accomplished via RBP. Retinol binding proteins have been identified within the uterus, embryo, and extraembryonic tissue of the bovine, ovine, and porcine, therefore RBP takes part in proper retinol exposure to the embryo and successful transport at the maternal-fetal interface.

Retinol Binding Protein-2 (RBP2) which is present in the small intestinal epithelium takes part in the uptake and intracellular metabolism of vitamin A. Vitamin A is a fat-soluble vitamin essential for growth, reproduction, differentiation of epithelial tissues, and vision. RBP2 moderates the supply of retinoic acid to the nuclei of endometrial cells throughout the menstrual cycle.

RBP1 is a member of the calycin superfamily and fatty-acid binding protein (FABP) family. RBP1 is the carrier protein which takes part in the transport of retinol (vitamin A alcohol) from the liver storage site to peripheral tissue. Additionally, RBP1 performs as a bridging molecule to recruit histone deacetylases (HDACs) which is a forceful regulator of gene expression. RBP1 is found in almost all the tissues with higher expression in pancreas, adrenal gland and pituitary gland, fetal liver and adult ovary.

Human Retinol Binding Protein, also known as RBP, is responsible for transporting and binding vitamin A. Human RBP has a binding site for 1 molecule of retinol and circulates in the plasma together with prealbumin as a protein complex. The prealbumin binding prevents greater glomerular losses of the human RBP. Only the retinol-free form of the RBP, which has no affinity for prealbumin, undergoes glomerular filtration unhindered as a result of its low Mw. Human RBP is re-absorbed by the tubular cells and catabolized there.