Human Alpha2-HS glycoprotein (AHSG), a glycoprotein synthesized by hepatocytes, was
expressed in insect cells using the recombinant baculovirus system. The protein was
purified from the cell supernatant, and appeared as a single band at about 52 kDa.
Western blot using a specific antibody to the Bchain of AHSG indicated that the connecting
peptide was present in the protein. When incubated with solubilized insulin receptors,
recombinant AHSG inhibited the tyrosine kinase activity of the receptors in a dose-dependent
fashion at concentrations in the range of those of the circulating protein. AHSG did
not interfere with the binding of insulin to its receptor. These results indicate
that human AHSG represents a natural inhibitor of the insulin receptor tyrosine kinase,
is active as a singlechain protein and possesses a biological role similar to that
of its homologue in rats, pp63, described by Auberger et al. (1).
Key words
Alpha2-HS Glycoprotein - Fetuin - pp63 - Recombinant Baculovirus - Insulin Receptor
- Tyrosine Kinase
