[Modification of the electric characteristics of bilayer lipid membranes by intramitochondrial thyroid hormone receptors].

Electric conductivity of flat bilayer lecithin membranes (BLM) which was initially equal to 10(-8) Sm/cm2 increased about 10-fold after addition to the medium of proteins isolated from rat liver mitochondria, characterized by high affinity for thyroid hormones (the association constant for 125I-thyroxine = 3.5 10(8)M-1). In that case there was an increase in electric stability of the BLM as judged from an over 2-fold increase in the potential of electric breakdown of such membranes as compared with unmodified BLM. Addition of L-thyroxine (10(-7)M) to the receptor-BLM system was accompanied by another increase in electric conductivity and reduction in the electric capacity of the membranes under study. It is assumed that the changes in the electric characteristics of the BLM in the presence of receptor and thyroxine were a consequence of specific interaction of the hormone molecules and receptor located on the membrane, since in the absence of the latter one, thyroxine did not provoke any changes in the BLM parameters under consideration.