Purification of the human anionic polypeptide fraction of the apo‐bile lipoprotein complex by zonal ultracentrifugation

Abstract

The two main proteic constituents of the human Apo-bile lipoprotein complex (BLC), i.e., the anionic polypeptide fraction (APF) and the IgA fragments, were separated by preparative zonal ultracentrifugation using a sucrose gradient containing 1.5 mM glycodesoxycholate. The purification of the APF was verified by sodium dodecyl sulphate (SDS) polyacrylamide gel electrophoresis and immunology, and its amino acid composition then was determined. This procedure was used to obtain a polyclonal antiserum directed solely against the APF.

Involvement of osteopontin as a core protein in cholesterol gallstone formation

“…The studies of Lafont et al and Ostrow et al have independently found the same anionic calcium‐binding protein to be present in bile: a LMW acidic glycoprotein (MW approx. 10 kDa) isolated from hepatic bile, gallbladder bile, cholesterol gallstones, and pigment stones []. Shimizu et al [9] also isolated a LMW acidic glycoprotein capable of inhibiting the precipitation of calcium carbonate in a supersaturated solution; this proved to be the same protein as that reported by Lafont et al and Ostrow et al [] and it promoted nucleation in lithogenic bile.…”

“…10 kDa) isolated from hepatic bile, gallbladder bile, cholesterol gallstones, and pigment stones []. Shimizu et al [9] also isolated a LMW acidic glycoprotein capable of inhibiting the precipitation of calcium carbonate in a supersaturated solution; this proved to be the same protein as that reported by Lafont et al and Ostrow et al [] and it promoted nucleation in lithogenic bile. Proteolytic fragments and polymeric forms derived from Opn have also been recognized in bile, including a functional arginine–glycine–aspartate (RGD) cell‐binding domain.…”

“…Such matrix proteins have been reported in pancreatic and renal calculi []. A low‐molecular‐weight (<12kDa) acidic glycoprotein isolated from hepatic bile, gallbladder bile, cholesterol gallstones, and pigment stones, denoted an anionic polypeptide/calcium‐binding protein (APF/CBP), has been found to display calcium‐binding properties [].…”

Influence of Dehydrocholic and Cholic Acids on the Biliary Secretion of Anionic Polypeptide Fraction, the Major Apoprotein of the Biliary Lipoprotein Complex

“…Sccretion of bile salts into bile leads to the formation of lipoprotciri vesicles (BLC) able to transport free cholesterol and phospholipids (7). These vesicles are stabilized by a major anionic apoprotcin called APF closely associated with bile lipids in bile.…”

“…In BLC, biliary lipids are closely associated with a small, heat-stable, acidic amphipathic apoprotein called anionic polypeptide fraction (APF), with tightly bound bilirubin (7). In human bile, APF was recently purified by zonal ultracentrifugation, and polyclonal and monoclonal antibodies were obtained (8).…”