Transcortin in rat kidney: subcellular distribution of transcortin-synthesizing polyribosomes.

The [3H]corticosterone-transcortin complexes from kidney cytosol show elution positions on DEAE-cellulose identical to serum transcortin. The incorporation of 14C-labeled amino acids into anti-transcortin-precipitable material of kidney slices has been measured and compared with that of serum transcortin. It was established that kidney synthesized transcortin with an apparent molecular weight of 66 kDa on SDS-electrophoresis which resembles serum corticosteroid-binding globulin. Studies on the binding of [125I]anti-transcortin-IgG to membrane-bound rat kidney polyribosomes revealed an association of [125I]anti-transcortin-IgG with a discrete polyribosome fraction in the heavy polyribosome region; free polyribosomes were devoid of antigenic material able to bind antibodies to transcortin.