Merck, A4781-1G, Asialofetuin from fetal calf serum

General description
Asialofetuin is a glycoprotein with three asparagine-linked triantennary complex carbohydrate chains and terminal N-acetylgalactosamine residues.
Application
Asialofetuin from fetal calf serum has been used:
to quantitate the plant Ricin toxin′s B subunit (RTB) lectin activity in β-phaseolin signal peptide (P)–proinsulin gene (INS)–RTB plants by enzyme-linked immunosorbent assay (ELISA)
quantitate VP7:RTB fusion protein in transformed potato tissues by ELISA
as a glycoprotein substrate to measure the receptor-binding activity of recombinant RTB and NSP490–RTB fusion proteins
to study the nature of the interaction between ferritin and the placenta

Incorporation of asialofetuin (AF) in liposomes strongly enhance delivery to and endocytosis by cells displaying the AF receptor, notably hepatocytes. This provides a very efficient route for gene therapy.
Biochem/physiol Actions
Asialofetuin exhibits affinity to asialoglycoprotein receptor (ASGP-R) on hepatocytes and uses the receptor to enter the cell. This property allows asialofetuin to be used as a ligand to deliver drugs to hepatocytes and as a competitive inhibitor to ASGP-R.
Preparation Note
Prepared by a modification of Spiro, R.G., J. Biol. Chem., 235, 2860 (1960).