Functions as carrier for hydrophobic molecules in body fluids. Essential for the solubility and activity of lipidated Wnt family members, including WNT1, WNT2B, WNT3, WNT3A, WNT5A, WNT7A, WNT7B, WNT8, WNT9A, WNT9B, WNT10A and WNT10B (PubMed:26902720). Binds vitamin E. May transport vitamin E in body fluids under conditions where the lipoprotein system is not sufficient. May be involved in the transport of vitamin E across the blood-brain barrier (By similarity). Forms a 1:1 complex with Wnt family members; interacts with WNT3A and WNT5A (PubMed:26902720). Interacts with WNT1, WNT2B, WNT3, WNT7A, WNT7B, WNT8, WNT9A, WNT9B, WNT10A and WNT10B (By similarity). The second albumin domain forms a deep binding pocket that contains palmitoleic acid (in vitro). Palmitoleic acid is most likely not the physiological ligand. Instead, this pocket may accomodate the covalently bound lipid moiety of Wnt family members. N-glycosylated; more than 90% of the glycans are sialylated. Belongs to the ALB/AFP/VDB family.