Cytoskeleton

CYTOSKELETON

The cytoskeleton in eukaryotic cells consists of chains of proteins of three different types. These include microfilaments, intermediate filaments, and microtubules.

• Microfilaments—these are called actin filaments because they are mainly made from actin proteins. In fact, their major structure is that of two strands of actin protein wound in spiral formation. These are the thinnest of the fibers of the cytoskeleton. They act in the division of cytoplasm into two daughter cells, a process called “cytokinesis”. They aid in cell mobility of single-celled eukaryotic organisms so that cytoplasm can flow in one direction. They also act along with myosin to allow muscle cells to contract.

• Intermediate filaments—these are called “intermediate” because they are of a thickness between microfilaments and microtubules. They are made of multiple protein types, such as keratin, vimentin, lamin, and desmin. These (except for lamin) are found in the cytoplasm and function to maintain cell shape and