The mode of action on actin polymerization of skeletal muscle actin ADP-ribosylated on arginine 177 by perfringens iota toxin was investigated. ADP-ribosylated actin decreased the rate of nucleated actin polymerization at substoichiometric ratios of ADP-ribosylated actin to monomeric actin. ADP-ribosylated actin did not tend to copolymerize with actin. Actin filaments were depolymerized by the ...

Cyclase-associated protein (CAP) is a conserved actin-binding that regulates multiple aspects of actin dynamics, including polymerization, depolymerization, filament severing, and nucleotide exchange. CAP has been isolated from different cells tissues in an equimolar complex with actin, previous studies have shown CAP–actin contains six molecules each actin. Intriguingly, here, we successfully ...

Hair cell stereocilia structure depends on actin filaments composed of cytoplasmic β-actin and γ-actin isoforms. Mutations in either gene can lead to progressive hearing loss in humans. Since β-actin and γ-actin isoforms are 99% identical at the protein level, it is unclear whether each isoform has distinct cellular roles. Here, we compared the functions of β-actin and γ-actin in stereocilia fo...

Remodeling of the actin filament system in cells results from strictly regulated polymerization and depolymerization of actin, where hydrolysis of actin‐bound ATP is crucial. Actin–actin interactions are influenced by the state of the bound nucleotide, and many microfilament regulators influence the actin ATPase by binding preferentially either to ATP/ADP Pi‐ or ADP‐bound actin. This chapter su...

We have examined the role of feedback-regulation in the expression of the nonmuscle actin genes. C2 mouse myoblasts were transfected with the human beta- and gamma-actin genes. In gamma-actin transfectants we found that the total actin mRNA and protein pools remained unchanged. Increasing levels of human gamma-actin expression resulted in a progressive down-regulation of mouse beta- and gamma-a...

Branching filaments with striking perpendicularity form when actin polymerizes in the presence of macrophage actin-binding protein. Actin-binding protein molecules are visible at the branch points. Compared with actin polymerized in the absence of actin-binding proteins, not only do the filaments branch but the average length of the actin filaments decreases from 3.2 to 0.63 micrometer. Arrowhe...