(5The nucleation of actin filaments at the pm is frequently regulated by external signals, allowing the cell to change its shape and stiffness rapidly in response to changes in its external environment This nucleation is catalyzed by a complex of proteins that includes two actin-related proteins, or ARPS(Arp2 and arp3)
(5)The nucleation of actin filaments at the PM is frequently regulated by external signals, allowing the cell to change its shape and stiffness rapidly in response to changes in its external environment. This nucleation is catalyzed by a complex of proteins that includes two actin-related proteins, or ARPs(Arp2 and Arp3)
stress fiber filopodium cell cortex contractile bundle gel.like network tight parallel bundle 100nm Actin arrays in a cell
Actin arrays in a cell
Specific drugs affect polymer dynamics Cytochalasins: Prevent the addition of new monomers to existing MFS, which eventually depolymerize. Phalloidin: a cyclic peptide from the death cap fungus, blocks the depolymerization of mf Those drugs disrupt the monomer-polymer equilibrium, so are poisonous to cells
C. Specific drugs affect polymer dynamics Cytochalasins: Prevent the addition of new monomers to existing MFs, which eventually depolymerize. Phalloidin: A cyclic peptide from the death cap fungus, blocks the depolymerization of MF Those drugs disrupt the monomer-polymer equilibrium, so are poisonous to cells
D. Actin-binding proteins The structures and functions of cytoskeleton are mainly controlled by its binding proteins
D. Actin-binding proteins The structures and functions of cytoskeleton are mainly controlled by its binding proteins
2. 4 microfilament-binding proteins Actin binding proteins control the structure and behavior of actin filament actin binding proteins g. proflin(promote acting assembly), thymosin beta4(inhibits actin assembly) Some cytosolic proteins control actin polymerization 9 microfilament-binding proteins 3 different types of stalbe actin filament structures Q Parallel bundle: MFs isotactic parallel arrange, mainly found in microvillus and filopodium(z2 状伪足) ◆ Contractile bundle: MFS anti- parallel arrange, mainly found in stress fibers(应力纤维)and contractive ring of mitosis(有丝分裂收缩环)。 Ge- like network: MFs cross-linked arrange, most be found in cell cortex( stool,细胞皮层)
2.4 microfilament-binding proteins Actin binding proteins controlthe structure and behavior of actin filament. ◆ actin binding proteins e.g. proflin (promote acting assembly), thymosin beta4 (inhibits actin assembly). Some cytosolic proteins control actin polymerization. ◆ microfilament-binding proteins ◆ 3 different types of stalbe actin filament structures： ◆ Parallel bundle: MFs isotactic parallel arrange，mainly found in microvillus and filopodium (丝 状伪足). ◆ Contractile bundle: MFs anti-parallel arrange, mainly found in stress fibers (应力纤维) and contractive ring of mitosis(有丝分裂收缩环 )。 ◆ Gel-like network: MFs cross-linked arrange, most be found in cell cortex (cytosol, 细胞皮层)