Abstract
EM observations show that when aldolase binds to F-actin or F-actin-tropomyosin [ox muscle], highly ordered paracrystalline structures are formed consisting of tightly packed filament bundles cross-banded at 36 nm intervals. Morphologically different paracrystalline arrays are formed between aldolase and F-actin-tropomyosin-troponin. The filament bundles are far more extensive and are characterized by a prominent cross-striation at 38 nm intervals. This may reflect an interaction between troponin and aldolase.