Actin

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Actin filaments are 7 nm fibres [1]. They are present in both muscles and are a component of the cytoskeleton. Actin is particularly concentrated under the plasma membrane of a cell.

Structure:

These filaments help to maintain cell shape and are required for movement on the cell surface.

Actin hydrolyzes ATP to ADP when ATP is bound to the nucleotide binding site, changing the conformation of actin. Actin filaments are polarized, and facillitate the movement of cellular components.

Actin filaments can form various different structures, all with the common feature that they are cell surface projections. These structures could include microvilli, filopodia or lamellipodia [2].

Actin filaments can undergo nucleation and this takes place on the plasma membrane. This reaction is catalysed by several proteins, one of these know as ARP. This complex causes rapid elongation at the plus end of the actin, as it nucleates actin filament growth from the minus end. The reason this process occurs is to allow a cell to change shape, in order for it respond to changes within the external environment [3].

Also see actin filaments

Reference

  1. http://rpi.edu/dept/bcbp/molbiochem/MBWeb/mb2/part1/actin.htm
  2. Molecular biology of the cell, 4th edition, 2002, Bruce Alberts , Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts and Peter Walter. Page 931.
  3. Molecular biology of the cell, 4th edition, 2002, Bruce Alberts , Alexander Johnson, Julian Lewis, Martin Raff, Keith Roberts and Peter Walter. Page 931-932.
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