Isolation and partial purification of ceruloplasmin messenger RNA from rat liver

Partially purified ceruloplasmin mRNA was isolated using indirect immunoprecipitation of rat liver polysomes and poly(U)-Sepharose chromatography of polysomal RNA. This RNA programmed the synthesis of ceruloplasmin polypeptides in a cell-free system from mitochondria. Immunochemical analysis of the translation products revealed a 40-fold enrichment of the ceruloplasmin mRNA activity. The purified ceruloplasmin mRNA migrated as a major homogeneous component with an apparent molecular weight about 1×10⁶ daltons in polyacrylamide gels containing sodium dodecyl sulfate. The immunoprecipitated products of the cell-free translation had molecular weights in the range 4.5–5.4×10⁴ daltons as estimated by gel-electrophoresis under denaturating conditions. These values approach the weight of the half-molecule of native ceruloplasmin.