Cholesterol nucleation in bile

Protein factors, primarily glycoproteins, present in native human bile, have been found to modify, e.g., retard/accelerate, the process of de novo monohydrate crystal formation and, by inference, the rate of formation of cholesterol "nuclei" in such metastable cholesterol supersaturated systems. Neither the process of nucleation itself or how these modifiers work is yet well understood. From the health standpoint, an inhibitor type of protein has been found that may help explain why about 50% of the population have biliary cholesterol supersaturation; whereas, only about 10% actually form gallstones. To date, only one inhibitor glycoprotein has been isolated and characterized. Its role thus seems clear. This is in contrast to the situation with so-called promoter glycoproteins which accelerate nucleation and crystal formation. A number of these proteins have now been identified. An understanding of the comparative roles of each of these proteins has not yet been established. This is partly because of conflicting results, insufficient potencies or lack of information about physiologic concentrations.