[Transmembrane localization of cytosol proteins from the heart muscle in proteoliposomes].

It was shown that soluble cytoplasmic proteins of rabbit cardiac muscle were able to penetrate into phospholipid bilayer during preincubation with liposomes. The incorporation of cytoplasmic proteins into the liposomic membrane induced the sodium permeability that was sensitive to neurotoxins (veratridine and tetrodotoxin). This effect was partly eliminated by addition of tetrodotoxin to the external medium and completely eliminated in the presence of tetrodotoxin on the both sides of the liposomic membrane. It was found also that some of the proteins incorporated into the liposomes become resistant to pronase digestion when the enzyme is added to external medium. At the same time pronase included in the internal volume of the proteoliposomes was able to digest partly proteoliposomic proteins. All these data support the ideas of the integral incorporation of soluble cytoplasmic proteins into the liposomic membrane and to the existence of cytoplasmic precursor of voltage-dependent sodium channel.