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D.Kurry Molecular KCUMB > Cytoskeleton 2 - Dr White > Flashcards

Cytoskeleton 2 - Dr White Flashcards

1
Q

Slides to be familiar with

A
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2
Q

Slides to be familiar with

A
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3
Q

How does listeria and ARP complex work together

A

Listeria usese surface protein called actA to activates Arp 2/3 complex and cause local nucleation of actin filaments which are cross linked

addition of actin branched filaments pushes the bacteria along and force pushes

(cofilin dissassembles branced actin)

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4
Q

What is cofilin?

A

Binds to ADP actin filaments annd accelerates disassembly

“actin depolymerization factor”

binds to oth actin filaments and free actin subinits

binding of cofilin forces the filaments to twist a little mre tightly and weakens the contacts b/w actin subunits making filaments more brittle and more easily cut

removes actin tail in listeria

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5
Q

What is gelsolin

A

severs actin filaments and binds to plus end

makes smaller filaments availble for elongation or disassembly

helps with new and rapid assembly or disassembly deponds on conditions sometimes polymerization and other depolymerization

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6
Q

What are the microtuble accessory proteins ?

A
  1. Tublin Dimers
  2. microtubles
  3. filaments cross linking
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7
Q

What is lysteria?

A

RANDOM iNFO

  • symptons are : heaches, stiff necks, confusion, loss of balance , convulsions, fevers, and muscle aches
  • causes food pausing if your immunologically deficient or immunocompromised
  • 10x more likly if pregnant
  • 1/5 ppl die
  • 20% fetal loss and 3% newborn death of cases ​

TEST INFO BELOW

  • PAthogenic bacteria that invades your intestinal cells
  • treated with IV antibiotics
  • Listeria attaches to receptors one enterocytes
  • enters and replicates in your intestinal cells
  • unusual behavior based on actin cytoskeleton and acessory proteins
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8
Q

What are the accessory proteins related to filament bundling, cross linking and attachemnt?

A

A actinin

fimbrin

filamin

spectrin

ERM family

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9
Q

What are the accessory proteins that affect actin subunits

A

ARP COMPLEX **** - ACtin related protein -> (listeria)

Formin

THymosin:

Profilin:

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10
Q

What is kinesin

A

Protein that uses an ATP to walk along a microtuble track to move vesicles

walk towards plus end of microtuble

carry a binding site in the tail for a membrane enclosed organekke

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11
Q

What is thymosin?

A

Thymosin: binds actin sub units, prevents assembly

regulations of availability of actin monomers for actin. keeps actin monomers soluble so they are readily avaible for generating filaments

actin monomers - thymosin are in locked state

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12
Q

what are the microtuble accessory proteins

A

Katanin : severs microtubles

MAPS: “microtuble associated protein)

  • stablizes tubles by binding along sides of microtubles
  • stabilize microtubles against dissembly *
  • inhibts switch from growing state to sjrinking state “catastrophe supressed and growth enhanced”

XMAP215

  • a microtuble associated protein that stabilizes plus ends and accelerates assembly
  • stabilizes free ends of microtuble and inhibits the switch from the growing to shrinking state
  • catastrophes supressed and growing enhanced

Kinesin 13

  • : enhances catastrophic disassembly at plus end
  • by lowering activation energy barrer that prevents microtuble from springing apart
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13
Q

What are dynein arms ?

A

MIcrotubule motors

  • MInus end directed mictotuble motor
  • largest of known moleuclar motors and the fastest

Cytoplasmic dyneins

  • vescicle trafficking, localization of golgi apparatus

Axonemal dynein

  • Specialized for rapid and efficient sliding movements of microtubles that drive the beating of cilia and flagella
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14
Q

What is profilin?

A

recruits actin monomers to actin filament for polymerization

  1. profilin binds to an actin monomer
  2. exposes sit of actin that binds to pplus end of actin filament
  3. addition of an actin monor induces confernation change in actin reduces affinity for profilin
  4. profilin faills off leaving actin filament on subunit longer
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15
Q

What is formin?

A

Formin - Nucleates the assembly of long, unbranced chains + remains associated witht the growing plus end

along with arp help catalzye and determine shape and movement of the cell surface

dimeric protieins that can jnucleate the formation of a new actin filament

causes growth of STRAIGHT AND UNBRANCED actin filaments

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16
Q

What is spectrin?

A

Atttaches cytoskeleton to membrane

Confers property of durbility and stability to RBCs

defective results in disease called hereditary spherocytosis (HS) fragile red blood cells and anemia

17
Q

Slides to be familiar with

A
18
Q

What does tropomodulin do?

A

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

Stablization

prevents assembly and disassembly at minus end

stabilizes actin filaments

19
Q

What is alpha actinin

A

CRoss links actin filaments into loose bundles, allowing myosin 2 to enter to make actin filaments contractile

alpha actinin and fimibrin tend to exclude one another because of different functions

20
Q

What is filamin

A

promatoes the formation of loose, highly viscous gel like networks by clamping together 2 actin filaments

cells require the actin gel in order to extend membrane projets

HELPS CELL CRAWL ACROSS SOLID SURFACE

cannot crawl without filamin

21
Q

What is ERM family?

A

The ERM (ezrin, radixin, moesin) attaches to cytoskeleton to membrane

mediates the attachemnts between actin and plasma membrane

two binding sites: one to bind to actin filament and one to bind to transmembrane protein

22
Q

What are the three types of actin filament acessory proteins?

A
  1. affect actin subunits
  2. affects actin filaments
  3. affects filament bundling, cross linking, and attachment to membranes
23
Q

What is tropomyosin?

A

Stabilizes filaments - prevens binding with other proteins.

24
Q

What is fimbrin?

A

Cross links actin flaments into tight bundles exulding myosin 2

25
Q

what is chemotaxis and list one example of it?

A

A cell movement in directon controlled by a gradient of diffusible chemical

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

26
Q
A
27
Q

What are two groups of cytoskeletal motor proteins? and how do they work?

A

Dyneins arms and kinesin

  • Bind to polarized cytoskeletal fialments
  • use eneregy dervived from ATP hydrolysis tp move steadily along filament
  • carry memrane enclosed organelles to appropriate locations
  • Cause sytoskeletal filaments to exert tension
  • slide against each other generating force that drives muscle contraction or cell division
  • associated with their filament tracks through head region
  • motor domain
    • Head (determines identy of track and direction of movement)
    • tail determines identity of the cargo repersents biological function of motor protein
  • hydrolzies ATP
28
Q

What are the accessory proteins that affects actin filaments ?

A
  • Stablilizing
    • Tropomodudlin
    • tropomyosin
    • capping proteins
  • Disassembly
    • Cofilin
    • gelsolin
      *
29
Q

What are the filament cross linking binding proteins?

A

Plectin: cross linking protien links microtubles to intermediate filaments

Tau: a map protein MAP2 both cause bunding of microtubles

MAP2 has a long projecting domain

  • forms bundles of stable microtubles that are kept widely spaced

TAU binds to microuble at both termini

  • shorting and forms bundles that are more closely packed mictotubles
30
Q

What is ARP complex?

A

ARP COMPLEX **** - ACtin related protein - nucleates assembly to form weblike, HIGHLY BRANCHED chains and remains assocated with minus end (listeria)

ARP2 and ARP3 are 45% identical to actin

growth from minus end allowing for elongation at the plus end

requires activating factor

Works most efficiently when bound to sinde of pre exhisting actin filaments (cross link) at a 70 degree angle

31
Q

What are reuqies of cell crawling and why does this matter?

A
  • Cells must produce polarity (front vs rear)
  • Cells must move fowards but also must drage rear (retraction of rear of cell)
  • Important role in many cancers.
  • Cells invaved nieghboring tissues using this (metastases)
    • Crawl into blood or lymph vessels
32
Q

What are the tublin dimers

A

Strathming: binds suninots, prevents assembly

TIPS: the plus end tracking proteins growing plus ends and can link them to sttructures such as membranes

gamma - TuRc **** = nucleates the assmebly and remains assocaties witht the minus end

  • resonsible for mucleation fo microtuble growth
  • attached to centrosome at the minus end of the microtubles
  • serves as a template that creates a microtubles with 13 protofilaments
33
Q

what is a capping protein?

A

prevents assembly and siassembly at plus end .

binds to plus end and stabilizes actin filament

reduces rate of polymerization and depolymerization

D.Kurry Molecular KCUMB (33 decks)

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