BIO 201 Lecture Notes - Lecture 10: Myosin Head, Sarcomere, Actin
21 Feb 2017
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Muscle cells are multinucleated due to fusion of cells. Stimulation of neuron ca++ influx into muscle cells contraction. Approach: purify different proteins from muscle, attach each to glass slide, add fluorescent actin (capped at both ends to prevent polymerization/depolymerization, add atp. Atp hydrolyzes to adp when myosin slides by in. But if atp is non-hydrolyzable, it won"t be broken down to adp and actin floats away. Head + light chain binding domain + tail. Head binds actin and atp + hydrolyzes atp. Pulls towards (+) ends of actin mediates muscle contraction. Myosin head group pulls on actin filament. Adp is bound to head group or nothing. Atp binding allows myosin to release from head group. Atp hydrolysis is involved in contraction while binding of atp on myosin is involved in its release on actin. + ends of actin are anchored to z-line. When cell is stimulated, ca moves to + ends. When there"s a contraction, the sarcomere shortens.
