Dynactin Article - Schroer

Question 1

<p>Is p150Glued sufficient for binding dynein? Is it sufficient for allowing the motor to traverse the microtubule lattice over long distances?</p>

Answer 1

<p>Yes to both. </p>

Question 2

<p class=”large” style=”text-align:center”;>Do dynactin and kinesin II interact at all?</p>

Answer 2

<p class=”large” style=”text-align:center”;>Dynactin contributes to Kinesin II’s activity. It probably provides functions similar to those seen for dynein. </p>

Question 3

<p class=”large” style=”text-align:center”;>Is dynactin needed for viability? Is it needed for mitosis?</p>

Answer 3

<p class=”large” style=”text-align:center”;>Yes to both. </p>

Question 4

<p class=”large” style=”text-align:center”;>What is dynactin’s largest subunit?</p>

Answer 4

<p class=”large” style=”text-align:center”;>p150Glued</p>

Question 5

<p class=”large” style=”text-align:center”;>Does p150Glued have to be associated with other dynactin subunits to function properly?</p>

Answer 5

<p class=”large” style=”text-align:center”;>Yes; mutations that prevent glued from being incorporated into dynactin yield nonfunctional protein. </p>

Question 6

<p class=”large” style=”text-align:center”;>Where is most of dynactin’s mass contained?</p>

Answer 6

<p class=”large” style=”text-align:center”;>In its rod</p>

Question 7

<p class=”large” style=”text-align:center”;>How big is dynactin’s rod?</p>

Answer 7

<p class=”large” style=”text-align:center”;>10x40 nm</p>

Question 8

<p class=”large” style=”text-align:center”;>How big is dynactin’s arm?</p>

Answer 8

<p class=”large” style=”text-align:center”;>25-50nm</p>

Question 9

<p class=”large” style=”text-align:center”;>What do the globular termini of the arm contain?</p>

Answer 9

<p class=”large” style=”text-align:center”;>A microtubule binding site</p>

Question 10

<p class=”large” style=”text-align:center”;>Where do dynein and other motors bind dynactin?</p>

Answer 10

<p class=”large” style=”text-align:center”;>Along or near the base of the arm.</p>

Question 11

<p class=”large” style=”text-align:center”;>What does the rod-like domain probably bind? </p>

Answer 11

<p class=”large” style=”text-align:center”;>A variety of membranous and proteinaceous structures. </p>

Question 12

<p class=”large” style=”text-align:center”;>What happens when you decouple the rod from the arm? </p>

Answer 12

<p class=”large” style=”text-align:center”;>Issues with subcellular organization and motility. </p>

Question 13

<p class=”large” style=”text-align:center”;>How many different subunits does dynactin have?</p>

Answer 13

<p class=”large” style=”text-align:center”;>11, but some have more than one copy.</p>

Question 14

<p class=”large” style=”text-align:center”;>What subunits are contained in the Arp1 rod?</p>

Answer 14

<p class=”large” style=”text-align:center”;>Arp1, Arp11, Actin, CapZ, p62, p27, and p25</p>

Question 15

<p class=”large” style=”text-align:center”;>What does Arp1 stand for?</p>

Answer 15

<p class=”large” style=”text-align:center”;>Actin-related protein 1</p>

Question 16

<p class=”large” style=”text-align:center”;>How is Arp1 like actin? How is it different from actin?</p>

Answer 16

<p class=”large” style=”text-align:center”;>It can hydrolyze ATP and form filaments. But filaments are short, stable, and of uniform length, so it is probably less dynamic and can govern its own assembly. </p>

Question 17

<p class=”large” style=”text-align:center”;>What notable protein can Arp1 bind?</p>

Answer 17

<p class=”large” style=”text-align:center”;>beta III spectrin, a specialized isoform found on golgi membranes</p>

Question 18

<p class=”large” style=”text-align:center”;>What is on the two ends of the Arp1 rods?</p>

Answer 18

<p class=”large” style=”text-align:center”;>CapZ is on one end (the end most similar to the + end of actin); a heterotetrameric complex containing Arp11, p62, p25, and p27 are on the opposite end. </p>

Question 19

<p class=”large” style=”text-align:center”;>Does dynactin contain beta actin?</p>

Answer 19

<p class=”large” style=”text-align:center”;>Seems to – results vary. If it does, it’s only a single monomer. </p>

Question 20

<p class=”large” style=”text-align:center”;>p62</p>

Answer 20

<p class=”large” style=”text-align:center”;>A dynactin subunit, a protein of 53 kDa with a zinc binding motif (RING or LIM domain) near the N terminus. This might participate in binding to Arp1, Arp11, or other dynactin subunits, or to other subcellular structures. Loss of p62 does not appear to significantly impact dynactin stability. </p>

Question 21

<p class=”large” style=”text-align:center”;>What are the two smallest dynactin subunits?</p>

Answer 21

<p class=”large” style=”text-align:center”;>p25 and p27</p>

Question 22

<p class=”large” style=”text-align:center”;>What do p62, Arp11, p25, and p27 form?</p>

Answer 22

<p class=”large” style=”text-align:center”;>A heterotetrameric complex that sits at the end of the Arp1 rod opposite CapZ. </p>

Question 23

<p class=”large” style=”text-align:center”;>Which is more highly conserved – rod subunits, or arm subunits?</p>

Answer 23

<p class=”large” style=”text-align:center”;>Rod subunits!</p>

Question 24

<p class=”large” style=”text-align:center”;>What subunits compose the arm?</p>

Answer 24

<p class=”large” style=”text-align:center”;>p150Glued, Dynamitin, p24/p22</p>

Question 25

<p class=”large” style=”text-align:center”;>What are the genes that correspond to these subunits? </p>

Answer 25

<p class=”large” style=”text-align:center”;>DCTN1 = p150Glued, DCTN2 = Dynamitin, DCTN3 = p24/22</p>

Question 26

<p class=”large” style=”text-align:center”;>What is the significance of coiled-coil interactions in the dynactin arm?</p>

Answer 26

<p class=”large” style=”text-align:center”;>It seems to allow them to associate and contribute to intersubunit interactions between all three components of the dynactin arm </p>

Question 27

<p class=”large” style=”text-align:center”;>How many copies of dynamitin are in each dynactin molecule?</p>

Answer 27

<p class=”large” style=”text-align:center”;>4 copies</p>

Question 28

<p class=”large” style=”text-align:center”;>How many copies of p150Glued are in each dynactin molecule?</p>

Answer 28

<p class=”large” style=”text-align:center”;>2 copies</p>

Question 29

<p class=”large” style=”text-align:center”;>How many copies of p24/22 are in dynactin?</p>

Answer 29

<p class=”large” style=”text-align:center”;>2 copies</p>

Question 30

<p class=”large” style=”text-align:center”;>Which dynactin subunit was the first to be cloned and sequenced?</p>

Answer 30

<p class=”large” style=”text-align:center”;>p150Glued</p>

Question 31

<p class=”large” style=”text-align:center”;>How many globular heads are there at the tip of the dynactin arm (in one dynactin complex)?</p>

Answer 31

<p class=”large” style=”text-align:center”;>2 – because there are 2 p150 copies</p>

Question 32

<p class=”large” style=”text-align:center”;>Which amino acids contain the CAP-Gly motif? </p>

Answer 32

<p class=”large” style=”text-align:center”;>Aa 1-110</p>

Question 33

<p class=”large” style=”text-align:center”;>Does p135 encode the CAP-Gly domain? </p>

Answer 33

<p class=”large” style=”text-align:center”;>no</p>

Question 34

<p class=”large” style=”text-align:center”;>What are some reasons CAP-Gly is important?</p>

Answer 34

<p class=”large” style=”text-align:center”;>Necessary for its ability to enhance the processivity of the dynein motor. Necessary for neuronal function in vivo. Contributes to microtubule minus-end anchoring at interphase centrosomes and mitotic spindle poles. </p>