Retinol Binding Protein

Retinol-binding proteins (RBPs) are specialized transporters that mediate the delivery and intracellular trafficking of retinol, a critical form of vitamin A, to target tissues and cellular compartments^[1]^[2]. Cellular retinol-binding protein I (CRBP-I) facilitates retinol storage in lipid droplets and directs its oxidation to retinoic acid via cytosolic enzymes, ensuring controlled bioavailability for nuclear receptor-mediated gene regulation^[3]^[4]^[5]. Mechanistically, holo-CRBP is recognized by specific enzymes such as retinaldehyde dehydrogenases, which catalyze retinoic acid formation without requiring dissociation of retinol from the binding protein, whereas apo-CRBP can inhibit this process, highlighting isoform-specific interactions^[3]^[6]. In disease models, decreased CRBP-I expression is associated with impaired retinoic acid receptor (RAR) activation, loss of epithelial differentiation, and enhanced tumorigenicity in breast tissue^[5]. Compared with related isoforms, including CRBP-II and CRABPs, CRBP-I exhibits unique subcellular localization, ligand specificity, and kinetic control over retinol metabolism, which distinguishes its functional role in retinoid signaling^[6]^[7]. Retinol-binding proteins have also been leveraged experimentally to manipulate retinoid availability, enabling studies of retinoid-dependent differentiation, metabolic regulation, and embryonic development in both in vitro and in vivo models^[8]^[9]^[7].

References:

[1]. Wolf G. Cellular retinol-binding protein functions in the regulation of retinoid metabolism. Nutr Rev. 1992 Jul;50(7):197-9. doi: 10.1111/j.1753-4887.1992.tb01325.x. PMID: 1641199. et al. Cellular retinol-binding protein functions in the regulation of retinoid metabolism. Nutr Rev. 1992 Jul;50(7):197-9.

[2]. Sani BP, et al. Novel retinoid-binding proteins from filarial parasites. Biochem J. 1985 Dec 1;232(2):577-83.

[3]. Ottonello S, et al. Retinol bound to cellular retinol-binding protein is a substrate for cytosolic retinoic acid synthesis. J Biol Chem. 1993;268(36):27133-27142.

[4]. Molotkov A, et al. Opposing actions of cellular retinol-binding protein and alcohol dehydrogenase control the balance between retinol storage and degradation. Biochem J. 2004 Oct 15;383(Pt 2):295-302.

[5]. López de Haro MS, et al. Binding of retinoids to uteroglobin. FEBS Lett. 1994 Aug 1;349(2):249-51.

[6]. Olsen T, et al. Retinol, Retinoic Acid, and Retinol-Binding Protein 4 are Differentially Associated with Cardiovascular Disease, Type 2 Diabetes, and Obesity: An Overview of Human Studies. Adv Nutr. 2020 May 1;11(3):644-666.

[7]. Napoli JL. Cellular retinoid binding-proteins, et al. Cellular retinoid binding-proteins, CRBP, CRABP, FABP5: Effects on retinoid metabolism, function and related diseases. Pharmacol Ther. 2017 May;173:19-33.

[8]. Kanai M, et al. Retinol-binding protein: the transport protein for vitamin A in human plasma. J Clin Invest. 1968 Sep;47(9):2025-44.

[9]. Lotan R. A crucial role for cellular retinol-binding protein I in retinoid signaling. J Natl Cancer Inst. 2005 Jan 5;97(1):3-4. doi: 10.1093/jnci/dji031. PMID: 15632368. et al. A crucial role for cellular retinol-binding protein I in retinoid signaling. J Natl Cancer Inst. 2005 Jan 5;97(1):3-4.

[10]. Farias EF, et al. Cellular retinol-binding protein I, a regulator of breast epithelial retinoic acid receptor activity, cell differentiation, and tumorigenicity. J Natl Cancer Inst. 2005 Jan 5;97(1):21-9. [Content Brief]

[11]. Ong DE. Cellular transport and metabolism of vitamin A: roles of the cellular retinoid-binding proteins. Nutr Rev. 1994 Feb;52(2 Pt 2):S24-31. doi: 10.1111/j.1753-4887.1994.tb01383.x. PMID: 8202279. et al. Cellular transport and metabolism of vitamin A: roles of the cellular retinoid-binding proteins. Nutr Rev. 1994 Feb;52(2 Pt 2):S24-31.

[12]. Rao MR, et al. Isolation and characterization of binding proteins for retinol from the cytosol, nucleosol and chromatin of the oviduct magnum of laying hens. Biochem J. 1979 Dec 1;183(3):501-6.

[13]. Saari JC, et al. Identification of the endogenous retinoids associated with three cellular retinoid-binding proteins from bovine retina and retinal pigment epithelium. J Biol Chem. 1982;257(22):13329-13333.

Retinol Binding Protein Related Products (2):

By Type:	Selective (1)
By Effects:	Inhibitor (1) Antagonist (1)

Cat. No.	Product Name	Effect	Purity

HY-123623

Tinlarebant	Antagonist	98.05%
Tinlarebant (LBS-008) is an orally active non-retinoid RBP4 (retinol-binding protein 4) antagonist. Tinlarebant can be used for the research of the Stargardt disease.

HY-185133

RBP4-IN-3	Inhibitor
RBP4-IN-3 (Compound 38) is a retinol-binding protein 4 (RBP4) inhibitor. RBP4-IN-3 can be used in studies related to cardiovascular diseases and obesity.

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