Sandbox Reserved 930: Difference between revisions
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[[Image:Actin myosin anim.gif|300px|left|thumb| The movement of myosin motor domain on actin filament, [[1cnt]]]] | [[Image:Actin myosin anim.gif|300px|left|thumb| The movement of myosin motor domain on actin filament, [[1cnt]]]] | ||
[[Image:myosin.png|300px|right|thumb| The contractile cycle of the myosin head]] | [[Image:myosin.png|300px|right|thumb| The contractile cycle of the myosin head]] | ||
In the striated muscle the actin and myosin proteins form ordered basic units called sarcomeres. Muscle contraction is achieved by the mechanical sliding of myosin filament (thick filament) along the actin filament (thin filament). The major constituent of the myosin filament is myosin, a motor protein responsible for converting chemical energy to mechanical movement. In the presence of Ca2+ and Mg2+, myosin is able to cyclically bind ATP and hydrolyse it to ADP + Pi, triggering subsequent myosin-actin detachment, reattachment and power stroke, so called contractile reaction (Fig.1). | |||
In the striated muscle the actin and myosin proteins form ordered basic units called sarcomeres. Muscle contraction is achieved by the mechanical sliding of myosin filament (thick filament) along the actin filament (thin filament). The major constituent of the myosin filament is myosin, a motor protein responsible for converting chemical energy to mechanical movement. In the presence of Ca2+ and Mg2+, myosin is able to cyclically bind ATP and hydrolyse it to ADP + Pi, triggering subsequent myosin-actin detachment, reattachment and power stroke, so called contractile reaction (Fig.1). | |||
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==Nucleotide binding pocket: ADP + Mg2+== | ==Nucleotide binding pocket: ADP + Mg2+== | ||
The nucleotide-binding pocket is located at the interface of the 50 kDa upper subdomain and the N-terminal subdomain, which is opposite a deep cleft that bisects the actin-binding domain (the domain picture).This part of protein involves an arrangement of a secondary structure mainly around the parallel 7-stranded β-sheet (reference 1). Loops extending from b-strands interact with the adenine nucleotide. | The nucleotide-binding pocket is located at the interface of the 50 kDa upper subdomain and the N-terminal subdomain, which is opposite a deep cleft that bisects the actin-binding domain (the domain picture).This part of protein involves an arrangement of a secondary structure mainly around the parallel <scene name='57/579700/Strands/1'>7-stranded β-sheet</scene> (reference 1). Loops extending from b-strands interact with the adenine nucleotide. | ||
ADP forms hydrogen bonds with the amino acide side chain around it (Scene), Mg2+ coordinates with side chains Thr183, Ser 241 of heavy chain, O1B and O3B from ADP and three water molecules (Scene) as well. The hydrogen bonds forming between ADP and side chains together with Mg2+ keeps ADP in the nucleotide-binding pocket. | ADP forms hydrogen bonds with the amino acide side chain around it (Scene), Mg2+ coordinates with side chains Thr183, Ser 241 of heavy chain, O1B and O3B from ADP and three water molecules (Scene) as well. The hydrogen bonds forming between ADP and side chains together with Mg2+ keeps ADP in the nucleotide-binding pocket. | ||
