Lecture 16 - The Cytoskeleton 2 Flashcards
What effect does kinesin-13 have on microtubules?
-separates protofilaments on free end facilitating depolymerization
What effect does spectrin have on actin?
- connects actin filaments to cell membrane
- responsible for durability ad stability of RBCs
What effect do MAPs have on microtubules?
- bind the side of microtubules
- stabilizes microtubules preventing disassembly
- suppresses catastrophe and enhances growth
What effect does the ARP complex have on actin?
- consists of Arp2, Arp3, and activating factor
- Arp2 and Arp3 are very similar to actin
- branched growth
- activating factor causes conformation change to mimic plus end of actin allowing polymerization
- skips nucleation; allowing rapid growth
- responsible for the behavior of Listeria
What effect does filamin have on actin?
- links two actin filaments together in a right angle
- forms a gel-like network
- used to hold cell membrane projections
- used in cell crawling
What is the general structure of a cytoskeleton motor protein?
Motor domain (head):
- determines direction of movement
- ATPase function
Tail:
-determines cargo bound
What proteins is responsible for propelling Listeria?
- ARP complex
- branching actin polymerization propels the bacteria
What effect does tropomodulin have on actin?
- binds minus end of actin filaments
- prevents disassembly
- stabilizes long living filaments
What effect do capping proteins have on actin?
- bind plus end preventing polymerization and depolymerization
- stabilizes filament
What affect does the ERM family have on actin?
-mediates attachment of actin filaments to the plasma membrane via transmembrane proteins
What effect does TIPS have on microtubules?
-associates with plus end and links to structures such as membranes
Dysfunction of what actin binding protein results in anemia?
- spectrin which is used in binding actin to cell membrane
- spectrin is responsible for the flexibility and durability of RBCs
What effect does stathmin have on microtubules?
-binds dimers and prevents assembly
What effect does α-actinin have on actin?
- cross links filaments into loose bundles
- allows binding of myosin II
What effect does fimbrin have on actin?
- cross links filaments into tight bundles
- does not allow for myosin II binding
What is Listeria and what is special about how it uses host cells?
- pathogenic bacteria
- it recruits cellular actin and accessory proteins to propel it
What effect does γ-TuRC have on microtubules?
- γ-tubulin ring complex
- responsible for nucleation of microtubules
- found in microtubule-organizing center (MTOC)/centrosome
What effect does formin have on actin?
- dimeric protein associated with plus end
- binds monomers and facilitates linear polymerization
Helps in FORMINg actin polymers
What effect does plectin have on microtubules?
-cross links microtubules to intermediate filaments
What effect does Tau have on microtubules?
- binds microtubules at both the N- and C- terminus
- forms short projecting loop
- closely packed microtubule bundle
What protein is responsible for depolymerization of Listeria comet trails?
-cofilin
What effect does cofilin have on actin?
- binds actin filaments and twists them facilitating disassembly
- also called “acting depolymerizing factor”
What effect does Katanin have on microtubules?
- severs microtubules
- comes from the Japanese work for “sword”
What effect does XMAP215 have on microtubules?
- xenophobia microtubule-associated protein (215 kDa)
- stabilizes free end of microtubules
- suppresses catastrophe and enhances growth
What effect does tropomyosin have on actin?
- binds actin filaments preventing binding of other accessory proteins
- stabilizing
What effect does thymosin have on actin?
- binds actin monomers preventing polymerization
- “stores” monomers so they are available for polymerization later
What effect does gelsolin have on actin?
- severs actin filament and binds to plus end
- creates smaller filaments
- can promote polymerization or depolymerization
What are the different categories of cytoskeletal motor proteins and what differentiates them?
Kinesin:
-movement in the plus end
Dynein:
-movement towards the minus end
What effect does profilin have on actin?
- binds actin monomers exposing binding sites
- facilitates polymerization
What effect does MAP2 have on microtubules?
- binds microtubules with long protruding domain with additional microtubule binding domain
- widely spaced microtubules
