Retinol-binding protein that mediates retinol transport in blood plasma. Delivers retinol from the liver stores to the peripheral tissues (PubMed:4708098). Transfers the bound all-trans retinol to STRA6, that then facilitates retinol transport across the cell membrane (By similarity). Interacts with TTR (PubMed:4708098). Interaction with TTR prevents its loss by filtration through the kidney glomeruli (Probable). Interacts with STRA6 (By similarity). Detected in blood plasma (at protein level). Belongs to the calycin superfamily. Lipocalin family.