About Human Retinol Binding Protein 4 (RBP4) Protein

Retinol Binding Protein 4 (RBP4), also known as Plasma Retinol-Binding Protein, is a member of the lipocalin family and serves as the principal carrier protein for retinol (vitamin A alcohol) in the circulation. Encoded by the RBP4 gene, RBP4 is synthesized predominantly in the liver and, to a lesser extent, in adipose tissue. The protein binds retinol with high affinity and transports it from hepatic vitamin A stores to peripheral tissues where vitamin A is required for vision, immune function, cellular differentiation, embryonic development, and metabolic regulation. In circulation, the retinol-RBP4 complex associates with transthyretin (TTR), which prevents renal filtration and prolongs its half-life in plasma.

Beyond its classical role in vitamin A transport, RBP4 has emerged as an important adipokine involved in metabolic regulation. Elevated circulating RBP4 levels have been associated with insulin resistance, obesity, type 2 diabetes, metabolic syndrome, cardiovascular disease, and chronic inflammatory conditions. Studies suggest that RBP4 can influence glucose metabolism, inflammatory signaling pathways, and adipose tissue function independently of its role in retinol transport. As a result, RBP4 has attracted significant interest as both a biomarker and potential therapeutic target in metabolic disease research.

RBP4 delivers retinol to target cells through interaction with specific cell-surface receptors, including STRA6 (Stimulated by Retinoic Acid 6), facilitating cellular uptake and regulation of retinoid-dependent signaling pathways. Defects in RBP4 expression or function can disrupt vitamin A homeostasis and have been linked to developmental abnormalities, visual disorders, metabolic dysfunction, and cardiovascular disease.

eEnzyme's Human RBP4 Protein is a high-quality recombinant protein suitable for studies of vitamin A transport, receptor-ligand interactions, metabolic disease mechanisms, biomarker development, antibody production, and drug discovery applications. The protein can be used in functional assays, binding studies, ELISA development, and investigations of retinoid biology and metabolic regulation.

Applications of Human RBP4 Protein

• Vitamin A transport and retinoid biology studies
• Metabolic disease and diabetes research
• Insulin resistance investigations
• Obesity and adipokine signaling studies
• Receptor-ligand interaction assays
• Antibody development and characterization
• Biomarker and diagnostic assay development
• Drug discovery and screening applications

Biological Significance of RBP4

RBP4 is the primary transporter responsible for mobilizing vitamin A from hepatic stores and delivering retinol to peripheral tissues. Through this function, RBP4 supports numerous physiological processes, including vision, immune function, epithelial maintenance, reproduction, embryonic development, and cellular differentiation. The circulating retinol-RBP4-TTR complex ensures efficient systemic distribution of vitamin A while protecting the protein from rapid renal clearance.

In addition to its transport role, RBP4 functions as an adipokine that influences glucose homeostasis, insulin sensitivity, inflammation, and lipid metabolism. Elevated RBP4 concentrations have been reported in obesity, insulin resistance, type 2 diabetes, cardiovascular disease, and metabolic syndrome, making it a valuable biomarker and emerging therapeutic target for cardiometabolic disorders. Ongoing research continues to explore the molecular mechanisms linking RBP4 to metabolic dysfunction and chronic inflammatory diseases.

Because of its dual role in vitamin A biology and metabolic regulation, RBP4 remains an important target in nutrition research, endocrinology, metabolic disease studies, and translational medicine. Human RBP4 Protein provides a valuable tool for investigating retinoid transport mechanisms, adipokine biology, and the development of novel diagnostic and therapeutic strategies.