Blog / Microfilaments Composition And Role In Cleavage And Contractility

Microfilaments: composition and role in cleavage and contractility

Written by Cindy Ma on Feb 13, 2020

Microfilaments, which are the thinnest part of the cytoskeleton, are used to give shape to the cell and support all of its internal parts.

Of the three types of protein fibers in the cytoskeleton, microfilaments are the narrowest. They function in cellular movement, have a diameter of about 7 nm, and are made of two intertwined strands of a globular protein called actin. For this reason, microfilaments are also known as actin filaments.

Actin is powered by ATP to assemble its filamentous form, which serves as a track for the movement of a motor protein called myosin. This enables actin to engage in cellular events requiring motion such as cell division in animal cells and cytoplasmic streaming, which is the circular movement of the cell cytoplasm in plant cells. Actin and myosin are plentiful in muscle cells – when they slide past each other, your muscles contract. In animal cell division, a ring made of actin and myosin pinches the cell apart to generate two new daughter cells.

Microfilaments also provide some rigidity and shape to the cell. They can disassemble and reform quickly, thus enabling a cell to change its shape and move. White blood cells (your body’s infection-fighting cells) make good use of this ability. They can move to the site of an infection and engulf the pathogen.

Key Points

  • Microfilaments assist with cell movement and structure and are made of a protein called actin.
  • Actin works with another protein called myosin to produce muscle movements, cell division, and cytoplasmic streaming.

Key Terms

  • cytoskeleton: network of protein fibers that help with cellular movement and maintaining its structure/shape
  • actin: a globular structural protein that polymerizes in a helical fashion to form an actin filament (or microfilament)
  • myosin: a large family of motor proteins found in eukaryotic tissues, allowing mobility in muscles
  • microfilaments: thin protein fibers made of actin used for cellular movement and structural maintenance


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