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Flashcards in Dynactin Article - Schroer Deck (34):
1

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

Yes to both.

2

Do dynactin and kinesin II interact at all?

Dynactin contributes to Kinesin II's activity. It probably provides functions similar to those seen for dynein.

3

Is dynactin needed for viability? Is it needed for mitosis?

Yes to both.

4

What is dynactin's largest subunit?

p150Glued

5

Does p150Glued have to be associated with other dynactin subunits to function properly?

Yes; mutations that prevent glued from being incorporated into dynactin yield nonfunctional protein.

6

Where is most of dynactin's mass contained?

In its rod

7

How big is dynactin's rod?

10x40 nm

8

How big is dynactin's arm?

25-50nm

9

What do the globular termini of the arm contain?

A microtubule binding site

10

Where do dynein and other motors bind dynactin?

Along or near the base of the arm.

11

What does the rod-like domain probably bind?

A variety of membranous and proteinaceous structures.

12

What happens when you decouple the rod from the arm?

Issues with subcellular organization and motility.

13

How many different subunits does dynactin have?

11, but some have more than one copy.

14

What subunits are contained in the Arp1 rod?

Arp1, Arp11, Actin, CapZ, p62, p27, and p25

15

What does Arp1 stand for?

Actin-related protein 1

16

How is Arp1 like actin? How is it different from actin?

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.

17

What notable protein can Arp1 bind?

beta III spectrin, a specialized isoform found on golgi membranes

18

What is on the two ends of the Arp1 rods?

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.

19

Does dynactin contain beta actin?

Seems to – results vary. If it does, it's only a single monomer.

20

p62

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.

21

What are the two smallest dynactin subunits?

p25 and p27

22

What do p62, Arp11, p25, and p27 form?

A heterotetrameric complex that sits at the end of the Arp1 rod opposite CapZ.

23

Which is more highly conserved – rod subunits, or arm subunits?

Rod subunits!

24

What subunits compose the arm?

p150Glued, Dynamitin, p24/p22

25

What are the genes that correspond to these subunits?

DCTN1 = p150Glued, DCTN2 = Dynamitin, DCTN3 = p24/22

26

What is the significance of coiled-coil interactions in the dynactin arm?

It seems to allow them to associate and contribute to intersubunit interactions between all three components of the dynactin arm

27

How many copies of dynamitin are in each dynactin molecule?

4 copies

28

How many copies of p150Glued are in each dynactin molecule?

2 copies

29

How many copies of p24/22 are in dynactin?

2 copies

30

Which dynactin subunit was the first to be cloned and sequenced?

p150Glued

31

How many globular heads are there at the tip of the dynactin arm (in one dynactin complex)?

2 – because there are 2 p150 copies

32

Which amino acids contain the CAP-Gly motif?

Aa 1-110

33

Does p135 encode the CAP-Gly domain?

no

34

What are some reasons CAP-Gly is important?

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.