Fibronectin isoforms in plasma membrane domains of normal and regenerating rat liver

Plasma membrane fractions were obtained from the three surface domains of normal and regenerating adult rat livers. It was shown by immunoblotting that sinusoidal plasma membranes contained the characteristic 220 and 210 kDa fibronectin doublet, whereas bile canalicular plasma membranes contained a 220 kDa component. In lateral plasma membranes, 180, 190 and 220 kDa fibronectin isoforms were present. Fibronectin in the sinusoidal and canalicular plasma membranes was shown, by detergent/aqueous phase partitioning, to be more hydrophilic than isoforms in lateral plasma membranes. Changes in the distribution of fibronectin between plasma membrane domains occurred during liver regeneration and their significance, especially in relation to cell division, is discussed.