Characterisation of a high-molecular-weight developmentally regulated adult rat liver-specific protein

A major, hitherto unknown protein which is shown to be developmentally regulated has been isolated from rat liver. The protein has a molecular mass of 150 kDa and constitutes 8-10% of the adult liver protein. Immunoblot experiments and immunofluorescence studies established its presence specifically in adult liver cells. This protein is not present in early embryonic liver cells, gets induced around day 18 of gestation and reaches near adult levels by 1 day after birth and is not found in the cells of an ascitic hepatoma. Unlike albumin and alpha-fetoprotein, the two well known developmentally regulated liver proteins, the 150 kDa protein is not secreted. Some of the characteristics of this liver-specific protein are discussed.