muscle contraction

In muscle and microtubule contraction {muscle contraction}|, protein slides along another protein by grabbing and pulling, using ATP.

process

Calcium ions are in muscle-cell sarcoplasmic reticulum. Calcium-ion release initiates sliding. If calcium ion is present, tropomyosin goes into actin helix groove, and calcium opens binding sites, so actin can bind. Then ATPase globule tilts 45 degrees, pulling actin along. Then actin releases. After contraction, tissue elasticity passively returns muscle to normal length.

myosin

Myosin has four light chains and two long alpha-helix chains, which make two beads at myosin end. Beads are ATPases, connect actin to myosin, and are where calcium ions act. Three thick myosins surround each thin actin.

actin

Actin is globular protein that polymerizes into globule helix. Six thin actin proteins surround each thick myosin protein.

tropomyosin

Tropomyosin molecule helically wraps around actin.

troponin

Troponin molecule has binding sites for calcium, tropomyosin, and actin.

Whole Section in One File

5-Chemistry-Biochemistry-Protein-Muscle Contraction

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Technical Information

Date Modified: 2022.0224