Through Thick and Thin—Interfilament Communication in Muscle

Abstract

Muscles contract via interaction between thick (myosin-containing) and thin (actin-containing) filaments in response to increased levels of calcium. During contraction, the myosin heads extend from the thick filament surface and attach to actin in the thin filaments, causing the filaments to slide past each other in a cyclic, ATP-driven process. Between contractions (the relaxed state), the myosin heads lie close to the thick filament surface, in an ordered arrangement, away from the thin filament (1).