Chapter 16 - Interphase

Lamellipodia and filopodia are examples of __________ that are driven by actin polymerization

membrane protrusions

Actin polymerizes at the __________ edge of a migrating cell, driving forward movement

leading

The energy source for actin filament polymerization is the hydrolysis of __________

ATP

The rearward movement of the actin network away from the leading edge is called __________

Retrograde flow

Retrograde flow is coupled to a dynamic process of filament turnover called __________

Treadmilling

The primary actin-depolymerizing factor involved in retrograde flow is __________

Cofilin

In lamellipodia, actin filaments are arranged in a __________ network, while in filopodia they are arranged in __________ bundles

branched, parallel

Stress fibers terminate at focal adhesions and are composed of actin filaments in __________ arrays crosslinked by __________ and associated with __________

Anti-parallel; α-actinin; Myosin II

Rho-family GTPases act as molecular __________ that regulate actin structures

Switches

The three key Rho-family GTPases involved in actin dynamics are __________, __________, and __________

Rho, Rac, Cdc42

Guanine nucleotide exchange factors (GEFs) activate GTPases by promoting exchange of __________ for __________

GDP, GTP

WASP family proteins are activated by __________ and promote actin polymerization by activating the __________ complex

Cdc42-GTP, ARP2/3

Formins are downstream effectors of __________ and nucleate __________ actin filaments

Rho-GTP, linear

Microinjection of Rac-GTP induces __________, while Cdc42-GTP induces __________ and Rho-GTP induces __________

Lamellipodia, filopodia, stress fibers

Actin helps drive endocytic vesicle formation via __________ actin assembly at the membrane

Branched

Endocytic vesicles can move on __________ near the cell surface and switch to __________ transport deeper in the cell

Actin, microtubule

Some endosomes generate movement via asymmetric actin polymerization, a phenomenon called __________

Endosome rocketing

Microtubules help organize and position organelles such as the __________ and __________

ER, Golgi

Anterograde transport refers to cargo movement from the __________ to the __________, while retrograde is the reverse

ER, plasma membrane

The (+) ends of microtubules are typically oriented toward the cell __________

periphery

Kinesins usually move toward the __________ end, while dyneins move toward the __________ end

positive, negative

Taxol __________ microtubules, while nocodazole __________ them

stabilizes, depolymerizes

After nocodazole washout, microtubules will __________ and organelles like the Golgi will __________

Re-polymerizes, reassemble near the centrosome

Golgi fragmentation occurs upon __________ of microtubules

disassembly

Stress fiber contraction is regulated by phosphorylation of __________ by __________

Myosin II light chains, Myosin Light Chains Kinase (MLCK)

Rho Kinase can also promote contraction by phosphorylating

Myosin II light chains