<P> Actin is a family of globular multi-functional proteins that form microfilaments . It is found in essentially all eukaryotic cells ( the only known exception being nematode sperm ) , where it may be present at a concentration of over 100 μM . An actin protein 's mass is roughly 42 - kDa , with a diameter of 4 to 7 nm , and it is the monomeric subunit of two types of filaments in cells : microfilaments , one of the three major components of the cytoskeleton , and thin filaments , part of the contractile apparatus in muscle cells . It can be present as either a free monomer called G - actin ( globular ) or as part of a linear polymer microfilament called F - actin ( filamentous ) , both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division . </P>
<P> Actin is a family of globular multi-functional proteins that form microfilaments . It is found in essentially all eukaryotic cells ( the only known exception being nematode sperm ) , where it may be present at a concentration of over 100 μM . An actin protein 's mass is roughly 42 - kDa , with a diameter of 4 to 7 nm , and it is the monomeric subunit of two types of filaments in cells : microfilaments , one of the three major components of the cytoskeleton , and thin filaments , part of the contractile apparatus in muscle cells . It can be present as either a free monomer called G - actin ( globular ) or as part of a linear polymer microfilament called F - actin ( filamentous ) , both of which are essential for such important cellular functions as the mobility and contraction of cells during cell division . </P>
where is the protein actin located in the body
where is the protein actin located in the body
found in essentially all eukaryotic cells ( the only known exception being nematode sperm )
found in essentially all eukaryotic cells ( the only known exception being nematode sperm )