Studies On human α₁-microglobulin VII

Production of α₁-microglobulin by a hepatoma cell line(C-Hc4)

Abstract

α₁-microglobulin(α₁-m)was detected by radioimmunoassay in the culture medium of a hepatoma cell line (C-Hc4). The level of this protein in the culture medium measured by radioimmunoassay increased proportionately with cell numbers. With the addition of puromycin and cycloheximide to the culture medium, the production of this protein was completely blocked. It was, therefore, suggested that this protein was actively produced by hepatoma cells.
This protein showed a complete immunochemical identity with purified α₁-m, serum and urinary α₁-m from a patient with renal insufficiency by Ouchterlony immunodiffusion and tandem crossed immunoelectrophoresis.
In crossed immunoelectrophoresis, this protein migrated at the α₁-region, being slightly slower than purified and serum α₁-m. On SDS disc electrophoresis combined with immune precipitation, this protein was also found to migrate slightly slower than purified α₁-m. These results might be caused by a minor difference of its constituent from that of the purifiedα ₁-m during the process of synthesizing this protein in hepatoma cells.