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Molecular Exam 2 > White- lecture 4 9/25 part 2 > Flashcards

White- lecture 4 9/25 part 2 Flashcards

1
Q

What are the 2 classes of the organization of the actin filaments?

A
  1. bundling proteins: alpha actinic and fimbrin

2. gel-forming protein: filamin

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2
Q

What is the function of alpha actinin?

A

cross links actin filaments into loose bundles allowing myosin 2 to make actin filaments contractile

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3
Q

What is the function of fimbrin?

A

cross links actin filaments into tight bundles excluding myosin 2

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4
Q

What is the function of filamin?

A

-promotes the formation of loose, highly viscous gel like networks by clamping together 2 actin filaments
-cells require the actin gel to extend to membrane projections
help cells crawl across a solid surface

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5
Q

What is the function of spectrin?

A

attaches to the membrane

confers the durability and stability of RBCs

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6
Q

What is hereditary spherocytosis?

A

A disease in which the spectrin of the RBC’s are defective and the RBCs are spherical and fragile

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7
Q

What makes up the ERM family?

A

ezrin, radixin, and moesin

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8
Q

What is the function of the ERM family?

A

mediates the attachment between actin and the plasma membrane

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9
Q

What 3 major groups do accessory proteins affect?

A
  1. tubulin dimers
  2. microtubules
  3. filament cross linking
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10
Q

What is the function of stathmin?

A

binds the subunits and prevents assembly to the tubulin dimers
affect actin

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11
Q

Define TIPS

A

the positive end tracking proteins; remains associated with the growing positive ends and can link them to structures such as membranes
affect actin

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12
Q

What is the function of yTuRC

A

nucleates assembly and remains associated with the negative end
microtubule growth
affect actin

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13
Q

Where are microtubules nucleated from?

A

microtubule organizing center (MTOC) and grow outward from the positive end

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14
Q

What is the y-tubulin ring complex?

A

responsible for the nucleation of the microtubule growth

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15
Q

What is the major MTOC of animals called?

A

a centrosome

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16
Q

Describe the nucleation of the microtubules within the centrosome

A

The microtubules are nucleated at the centrosome at the negative end with the positive end pointing outwards and the microtubules grow toward the cell periphery
star like

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17
Q

What is the function of katanin?

A

Severes microtubules

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18
Q

What is the function of MAPs? And what does it stand for?

A

stabilizes tubules by binding along the sides (microtubule associated protein)
stabilize the microtubules against assembly
2 domains; binding to microtubule, and the other that projects outward

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19
Q

What is the function of XMAP215?

A

a microtubule associated protein that stabilizes positive ends and accelerates assembly of microtubules

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20
Q

What is the function of Kinesin 13?

A
  • enhances catastrophic disassembly of microtubules at the positive end
  • increases the rate at which the microtubule switches from a growing to a shrinking state
  • binds to ends and pries filaments by lowering the activation energy barrier that prevents it from springing apart
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21
Q

How does the MAPs work?

A

Stabilizes the free ends of the microtubule and inhibits the switch from the growing to the shrinking state
surpasses catastrophes and growth is enhanced

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22
Q

How is the kinesis-13 able to pry the protofilaments apart?

A

Lowers the activation energy barrier that prevents a microtubule from springing apart

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23
Q

What is the function of plectin?

A

crosslinking protein, links microtubules to the intermediate filaments

24
Q

What is the function of Tau

A

MAP protein; bundling of microtubules

25
Q

What is the difference between the MAP2 and the Tau?

A

MAP2: long projecting domain, second microtubule binding domain a the other end; forms a bundle of microtubules that are kept widely spaced

Tau: binds to the microtubule to the N and the C terminal
short projecting loop
closely packed microtubules

26
Q

Describe cytoskeletal motor proteins

A
  • bind to polarized cytoskeletal filaments
  • energy derived from ATP hydrolysis to move steady along the filament
  • carry cargo to their locations
  • cause cytoskeletal filaments to exert tension
  • slide against each other generating a force that drives muscle contraction or cell division
27
Q

What are the functions of the head region of the motor proteins?

A

it is the motor domain (determines the identity of the track and the direction of movement around it)
hydrolyzes ATP

28
Q

What does the tail of the motor protein determine?

A

the identity of the cargo; have a binding site for membrane enclosed organelles

29
Q

What are the two major groups of the motor proteins>

A

kinesins and dyneins

30
Q

Define kinesin

A

a protein that uses ATP to walk along a microtubule track to move the vesicles
LARGE protein family with the domain as the only common element

31
Q

Where do most of the kinesins have the motor domain?

A

The N terminus of the heavy chain

32
Q

Where does kinesin move towards?

A

The positive end of the microtubule

33
Q

Define dynein

A

moves towards the negative end of the microtubule
2 or 3 heavy chains
largest and fastest motors

34
Q

What are the 2 major branches of the motor molecules?

A

cytoplasmic dyneins and axonemal dynein

35
Q

What is the function of a cytoplasmic dynein

A

vesicle trafficking, localization of the Golgi apparatus

36
Q

What is the function of an axonemal dynein

A

specialized for rapid and efficient sliding movements of a microtubule that drive the beating of cilia and flagella

37
Q

What are examples of short term cytoskeleton elements?

A

mitotic spindle

crawling across a solid surface

38
Q

What are examples of permanent cytoskeleton structures

A

cilia and flagella

39
Q

What is the role of cell crawling in cancer?

A

mets; invade neighboring tissues, crawl into lymph system carry to other sites

40
Q

Define chemotaxis

A

cell movement in a direction controlled by a gradient of a diffusible gradient

41
Q

Define neutrophils

A

toward a source of bacterial infection by detecting peptides that are derived from bacteria proteins

42
Q

Listeria

A

Pathogenic bacteria that invade your intestinal cells; ubiquitous in the soil and found on unwashed lettuce, animal products, dairy and meats; attaches to receptors on enterocytes and exhibit unusual behavior based on actin cytoskeleton and accessory proteins

43
Q

Symptoms of Listeria Infection

A

Headache, stiff neck, confusion, loss of balance, convulsions, fever and muscle aches

44
Q

ARP Complex (Actin Related Protein)

A

Nucleates assembly to form weblike, highly branched chains and remains associated with minus end; requires activating factor; most efficient when bound to the side of a preexisting actin filament (filaments cross linked)

45
Q

Formin

A

Nucleates assembly of long, unbranched chains and remains associated with growing plus end; each subunit has a binding site for an actin monomer

46
Q

Thymosin

A

Binds actin subunits, prevents assembly; regulates availability of actin monomers for actin polymerization

47
Q

Profilin

A

Binds actin subunits and speeds up elongation; recruits monomers to the actin filament for polymerization

48
Q

Where does the nucleation of actin filaments occur?

A

At or near the plasma membrane of cell

49
Q

Filament Nucleation

A

Process of formation of initial aggregate or nucleus

50
Q

Cofilin

A

Causes branched actin disassembly; binds to both actin filament and free actin subunits; forces filament to twist a little more tightly and weakens contact between actin subunits, making filament brittle and easier to cut; removes comet tail in Listeria

51
Q

Lamellipodia

A

Flat, protrusive veils

52
Q

Filopodia

A

Microvilli/spiky bundles

53
Q

Tropomodulin

A

Prevents assembly and disassembly at minus end, stabilizes actin filament, for long lived filament stabilization

54
Q

Tropomyosin

A

Stabilizes filament - prevents binding with other proteins; prevents actin filament from interacting with other proteins

55
Q

Capping Protein

A

Prevents assembly and disassembly at plus end; stabilizes actin filament and reduces rate of polymerization and depolymerization

56
Q

Gelsolin

A

Severs actin filaments and binds to plus end; makes smaller filaments available for elongation or disassembly; helps with new and rapid assembly or disassembly depending on conditions

Molecular Exam 2 (13 decks)

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