Antigen analysis of hepatic subcellular fractions

Abstract

Homogenates of rat liver were studied by immunoelectrophoretic methods. The total liver homogenate was injected in rabbits until obtaining a high level of antibodies. By means of immunoelectrophoresis the presence of 53 different antigens was demonstrated; their respec­tive mobilities are given as percentages referred to human albumin mobility.

It was found by direct immunoelectrophoresis and by absorption that 17 antigens were common to the rat blood se­rum. In the same way 14 antigens were found to be common to both liver and kidney. Finally, another 22 antigens were observed to be absent from serum and kidney.

Furtliermore the different subcellular hepatic fractions were analyzed; they were obtained by differential ultracentrifugation and their purity was checked by electron microscopy. The soluble cytoplasmic fraction gave 23 different antigens of which 10 were also found in se­rum and 7 in kidney. The microsomal fraction gave a total of 27 different antigens of which 9 were common to those of serum and 8 to those of kidney.

The internal and external mitochondrial membranes were analyzed separately. Antigenic analysis of the internal membranes showed the presence of 15 immunoelectrophoretic bands of precipitation of which 6 were in serum and 4 in kidney. The external membrane subfraction gave 4 different antigens, 2 of which are also present in rat serum.

Infernal and external mitochondrial membrane subfractions have only 2 com­mon antigens; these two are also pre­sent in serum.

A nomenclature system is proposed to distinguish and recognize each of the 53 different antigens according to the regions of the electrophoretogram of the whole rat liver on celulose acetate.

The antigens, whether belonging to serum only, either common or not with those of kidney are named according to the electrophoretic region in which they are found. The presence or absence of each antigen in the analyzed fractions is given along with some of its Chemical properties. Only 7 total liver antigens of the rat have not been found in any of the subcellular fractions, 2 in common and 3 not in common with those of kidney.

The specific and nonspecific antigens of each subcellular fraction are given also.