K+ localization in muscle cells by autoradiography, and identification of K+ adsorbing sites in living muscle cells with uranium binding sites in electron micrographs of fixed cell preparations.

Localization of K+-adsorption sites on two peripheral regions of the A band and the Z line in frog voluntary muscle cells has been demonstrated with the aid of autoradiography and radioactive 134Cs and 204 Tl. The findings confirm the association-induction hypothesis, according to which intracellular K+ is adsorbed on the beta- and gamma-carboxyl groups of intracellular proteins.