The binding of calcium ions by the isolated asialoglycoprotein receptor of hepatocytes and the inter-relationship between the calcium ion concentration and receptor function have been studied. The isolated receptor binds calcium ions only in the presence of asialoglycoprotein. The asialo-glycoprotein receptor complex binds 4 calcium ions; the binding exhibits marked positive cooperativity, and ...

Antibody-induced degradation and chemical cross-linking experiments have been carried out to assess the nature of the interaction between the two asialoglycoprotein-receptor polypeptides, H1 and H2, synthesized in HepG2 cells. Incubation of HepG2 cell monolayers with anti-H1 antibody caused a specific and equal loss of both H1 and H2 polypeptides. The same result was obtained with anti-H2 antib...

We recently synthesized a lipophilic prodrug of 9-(2-phosphonyl-methoxyethyl)adenine (PMEA), designated PMEA-LO, and incorporated it into reconstituted lactosylated high-density lipoprotein (LacNeoHDL). In a rat model, LacNeoHDL-associated PMEA-LO was internalized by the asialoglycoprotein receptor on parenchymal liver cells and converted into its active diphosphorylated metabolite. To further ...

Putative preneoplastic hepatocytes were isolated from male Fischer 344 rats treated with a single dose of diethylnitrosamine, 2-acetylaminofluorene feeding, and partial hepatectomy (Solt-Farber model). The isolation procedure involved, after collagenase dispersion of the liver, separation of the hepatocytes into small- and large-cell fractions by centrifugal elutriation, and subsequent selectio...

The asialoglycoprotein receptor from rat liver was purified by solubilization and affinity chromatography on asialoorosomucoid-Sepharose. The preparation yielded four distinct polypeptides of Mr 40,000-120,000. We prepared a monoclonal antibody that both immunoprecipitates solubilized receptor activity and blocks the binding of galactose-terminal glycoproteins to immobilized receptor. The monoc...

The stoichiometry and composition of membrane protein receptors are critical to their function. However, the inability to assess receptor subunit stoichiometry in situ has hampered efforts to relate receptor structures to functional states. Here, we address this problem for the asialoglycoprotein receptor using ensemble FRET imaging, analytical modeling, and single-molecule counting with photoa...