Abstract
A method for light microscopic localization of adenylate deaminase in sections of frozen rat quadriceps muscle is described. The method depends on the hydrolysis of 6-chloropurine ribonucleotide (the 6-chloroanalogue of adenylate) and the trapping of Cl minus by Ag plus. The resulting AgCl precipitate was made visible by exposing the sections to light. After this treatment black deposits about 1 mu in diameter were seen in muscle cells. These observations indicate that adenylate deaminase of rat quadriceps muscle is located at discrete sites within the muscle cells.