RELEASE OF RETINOL FROM RETINYL ESTERS A. Apo-CRBP Stimulates Hydrolysis of Endogenous Retinyl Esters Via a Chelate-Independent Process

Apo-CRBP 610 5 ~-Lactoglobulin None 2.5-90 BSA None 0.1-90 Apo-CRABP None 1-5 Holo-/apo-CRABP None 5 f!M each 3Retinol greater than in the control of an incubation done with microsomal protein alone. Retinol in the presence of apoCRBP was at least fourfold greater than control. bConcentration ranges of the proteins assayed: nine bovine serum albumin, five ~-lactoglobulin, and three CRABP concentrations were tested.