Myosin V is a two-headed myosin that is involved in organelle transport. How does its movement along actin filaments differ from that of myosin II?

Correct answer: It moves continuously (processively) without letting go of the filament.

Explanation

Different myosin superfamily members are adapted for different tasks. Myosin II is a low-processivity motor designed to work in large groups for contraction. Myosin V is a high-processivity motor, meaning a single molecule can take many steps without detaching, which is ideal for transporting cargo like organelles over long distances along an actin track.

Other questions

Question 1

Which of the three major types of cytoskeletal filaments are described as being responsible for determining the shape of the cell’s surface and for whole-cell locomotion?

Question 2

What is the approximate diameter of an actin filament, also known as a microfilament?

Question 3

Which feature of actin and tubulin subunits is responsible for the structural polarity of their respective filaments?

Question 4

In the context of actin polymerization, what term is used for the initial, inefficient process where small, unstable oligomers of actin are formed before rapid elongation can begin?

Question 5

What is the primary function of the Arp2/3 complex in actin filament organization?

Question 6

The drug Taxol, which is used in cancer treatment, affects the cytoskeleton by which mechanism?

Question 7

In the structure of a sarcomere, what is the name of the enormous protein that acts as a molecular spring, positioning the thick filaments midway between the Z discs?

Question 8

What is the direct trigger for the initiation of muscle contraction in a skeletal muscle cell?

Question 9

How does the protein cofilin, also known as actin-depolymerizing factor, promote the disassembly of actin filaments?

Question 10

What is the approximate outer diameter of a microtubule, which is constructed from 13 parallel protofilaments?

Question 11

The rapid interconversion of a microtubule between a growing and a shrinking state at a uniform free tubulin concentration is known as what process?

Question 12

What type of tubulin is specifically involved in the nucleation of microtubule growth and is found enriched in the microtubule-organizing center (MTOC)?

Question 13

Intermediate filaments differ structurally from actin filaments and microtubules because their subunits are:

Question 14

The human genetic disease epidermolysis bullosa simplex, which causes skin blistering from slight mechanical stress, is caused by mutations in the genes for which protein?

Question 15

What is the primary function of the SUN-KASH protein complexes?

Question 16

Which class of motor proteins generally moves toward the minus end of microtubules?

Question 17

The axoneme, the core of motile cilia and flagella, has a characteristic arrangement of microtubules described as:

Question 18

What is the name of the bacterial homolog of actin that is essential for maintaining the rod shape of many bacteria?

Question 19

Which statement accurately describes the final assembled structure of an intermediate filament?

Question 20

According to the description of the myosin II mechanochemical cycle, in what state is the myosin head when it is in the 'rigor configuration'?

Question 21

In non-muscle cells, what protein family cross-links actin filaments at roughly right angles to promote the formation of a loose and highly viscous gel, like that in the cell cortex?

Question 22

What is the name of the protein that binds to tubulin heterodimers, prevents their addition to microtubules, and whose activity is inhibited by phosphorylation?

Question 23

During which mode of cell migration is a three-dimensional pseudopod formed by explosive actin polymerization at the leading edge, with reduced adhesion to the substratum enabling very rapid movement?

Question 24

What is the approximate number of myosin heads in a single bipolar thick filament from frog muscle?

Question 26

Which of the following proteins are microtubule motor proteins that use ATP hydrolysis to move cargo or slide filaments?

Question 27

The bacterial protein FtsZ is a homolog of which eukaryotic cytoskeletal protein and what structure does it form during cell division?

Question 28

What type of cell junction anchors intermediate filaments and connects epithelial cells into a sturdy sheet?

Question 29

In the process of treadmilling in an actin filament, what is occurring at the plus and minus ends of the filament when it is at steady state?

Question 30

What is the role of the troponin complex in vertebrate skeletal muscle contraction?

Question 31

Which of the following describes the function of formins?

Question 32

How many tubulin heterodimers per second are added to a microtubule that is growing at a rate of 2 micrometers per minute, given that the length of one dimer is 8 nm?

Question 33

Which myosin superfamily member is unique in that it moves toward the minus end of an actin filament?

Question 34

The assembly of a centriole, which forms the core of a centrosome and a basal body, exhibits a characteristic symmetry of:

Question 35

In the axon of a neuron, how are the microtubules oriented?

Question 36

What is the primary role of the protein plectin?

Question 37

What is the role of septin filaments in a budding yeast cell?

Question 38

Which statement accurately describes the activity of profilin in relation to actin polymerization?

Question 39

A single myosin II head cycles about how many times per second during the course of a rapid muscle contraction?

Question 40

The motor protein kinesin-1 moves along a microtubule protofilament in discrete steps. What is the approximate length of each step?

Question 41

In a migrating fibroblast, which Rho family GTPase is primarily responsible for the formation of an enormous lamellipodium extending from the entire circumference of the cell when it is constitutively activated?

Question 42

How many major families of intermediate filament proteins are there in vertebrate cells, as listed in Table 16-2?

Question 43

The movement of pigment granules (melanosomes) in fish melanophores is regulated by a tug-of-war between which two types of motors?

Question 44

Which statement best describes the primary cilia found on the surface of most animal cells?

Question 45

Familial hypertrophic cardiomyopathy, a common cause of sudden death in young athletes, is associated with subtle point mutations in the genes for which proteins?

Question 46

What is the name for the weblike sheath of modified endoplasmic reticulum that surrounds each myofibril and releases Ca2+ to trigger contraction?

Question 47

Which of the following cellular structures is built from actin filaments?

Question 48

The motor protein that uses the energy of ATP hydrolysis to depolymerize microtubule ends, rather than to walk along them, is:

Question 49

In a living cell, about 50 percent of the actin is in filaments, and 50 percent is soluble. This is possible despite the soluble monomer concentration being well above the critical concentration because:

Question 50

What is the name of the protein that functions as the bacterial homolog of tubulin?