An antibody has been isolated that binds to F-actin but not to G-actin. What structural feature (s) of F-actin do you suppose the antibody binds (i. e., how is the antibody able to distinguish between these two forms of actin) ?

F-actin is a double helical filament as opposed to G-actin, which is a globular protein. Each actin filament has two ends, called the plus and

the minus ends, which makes it recognizable from each other. This gives the structure a distinct polarity.

Explanation:

Actin is the most abundant protein that is found in almost all eukaryotic cells. Its a most important part cytoskeleton as its a monomeric subunits (size 42kDa) of two types of filaments i. e. microfilaments and thin filaments in cells. Actin is essentially required to maintain stability and morphogenesis of cell. It is involved in numerous significant processes such as endocytosis, cell division and migration. Actin is present in two forms:

•G-actin

•F-actin

The two forms of actin are different structurally.

G - actin is a globular shaped protein, usually present in free form (a monomer), having a tight binding site for another actin monomer. Each monomer has ATP. Upon polymerization of G-actin monomers, a polymer called F-actin filaments is form. This process is driven by hydrolysis of ATP.