Definition

1. Noun:
   • A protein complex in muscle fibers: "actomyosin" is a biochemical complex found within muscle cells.
   • Composed of myosin and actin: It is formed by the combination of two specific proteins: myosin (thick filaments) and actin (thin filaments).
   • Shortens when stimulated and causes muscle contractions: This complex is the fundamental unit responsible for muscle contraction. When a muscle is stimulated, the actomyosin complex undergoes a conformational change that causes the filaments to slide past each other, shortening the muscle fiber.

Usage Examples

• Noun:
  • The interaction within actomyosin is essential for muscle movement.
  • Researchers studied the properties of purified actomyosin.
  • The contraction mechanism depends on the cyclic formation and dissociation of actomyosin.

Advanced Usage

• "Actomyosin complex": Often used to specify the complete, functional protein assembly.
  • The force generated by the actomyosin complex powers cellular motility.
• "Actomyosin ATPase activity": Refers to the enzymatic activity of the complex, which hydrolyzes ATP to provide energy for contraction.
  • The rate of contraction is influenced by the actomyosin ATPase activity.
• "Actomyosin ring": In cell biology, refers to a contractile structure composed of actin and myosin used in processes like cytokinesis (cell division).
  • The formation of the actomyosin ring pinches the cell into two daughter cells.

Variants and Related Words

• Actin (n): A globular protein that forms microfilaments; a primary component of the actomyosin complex.
• Myosin (n): A motor protein that interacts with actin to generate force and movement.
• Myofibril (n): The long, cylindrical organelle within muscle cells that contains the organized arrays of actomyosin complexes.
• Sarcomere (n): The basic repeating unit of a myofibril, where actomyosin-mediated contraction occurs.

Synonyms

• Contractile apparatus: A broader term for the system of proteins, including actomyosin, that enables contraction.
• Motor protein complex: Highlights its function in converting chemical energy into mechanical movement.

Related Phrases

• Actomyosin cross-bridge: Refers to the temporary link formed between a myosin head and an actin filament during the contraction cycle.
  • The power stroke occurs when the actomyosin cross-bridge changes shape.
• Actomyosin-dependent contraction: Describes any contraction process that relies on this specific complex.
  • Cytoplasmic streaming in some cells is an actomyosin-dependent contraction.

Noun

1. a protein complex in muscle fibers; composed of myosin and actin; shortens when stimulated and causes muscle contractions