Retinol binding protein 4, also known as RBP4, is a transporter protein[5] for retinol (vitamin A alcohol). RBP4 has a molecular weight of approximately 21 kDa and is encoded by the RBP4gene in humans.[6][7] It is mainly, though not exclusively, synthesized in the liver and circulates in the bloodstream as a hepatokine bound to retinol in a complex with transthyretin. RBP4 has been a drug target for ophthalmology research due to its role in vision.[8] RBP4 may also be involved in metabolic diseases as suggested by recent studies.
^Rocchi M, Covone A, Romeo G, Faraonio R, Colantuoni V (March 1989). "Regional mapping of RBP4 to 10q23----q24 and RBP1 to 3q21----q22 in man". Somatic Cell and Molecular Genetics. 15 (2): 185–90. doi:10.1007/BF01535081. PMID2928844. S2CID37896530.