Distribution of antibodies to the troponin complex, troponin-C and troponin-I in chicken skeletal muscle as determined by a simplified method for immuno-electron microscopy.

Antisera against the troponin complex, troponin-C and troponin-I have been utilized to locate these proteins in normal, adult chicken skeletal muscle and in filaments prepared from chicken acetone dried powder. The antisera had been previously characterized by immunochemical methods and were employed to ascertain the distribution of the proteins by a simple method for immuno-electron microscopy. Glycerinated chicken breast muscle was treated with the antisera, unreacted antibody was washed from the muscle, and a goat anti-rabbit gamma-globulin was added to enhance the electron density of the antigen-antibody complexes. A periodic distribution of anti-troponin-C at a mean interval of 389 A was observed along the thin filaments in the sectioned tissue. Anti-troponin-I was deposited every 399 A (P less than 0-01). Thin filaments were prepared from acetone dried powder and reacted with the antisera. The anti-troponin-C was located every 389 A; anti-troponin-I, every 399 A (P less than 0-01). Our technique for immuno-electron microscopy is compared with that used by others, and the significance of the findings is discussed.