Cytoskeleton II Flashcards
In mitosis, spindle assembly and chromosomal alignment and segregation include ____ and ____.
Cytokinesis involves ____ and ____.
In mitosis, spindle assembly and chromosomal alignment and segregation include KINESINS and DYNEIN.
Cytokinesis involves ACTIN and MYOSIN II.
Formation of neural tube involves ____ of epithelial sheet caused by organized _____ of adhesion belts with associated ____ filaments. The ____ of the epithelial sheet is driven by ____-dependent contraction of the adhesion belt.
Formation of neural tube involves INVAGINATION of epithelial sheet caused by organized TIGHTENING of adhesion belts with associated ACTIN filaments. The FOLDING of the epithelial sheet is driven by MYOSIN-II-dependent contraction of the adhesion belt.
All three classes of cytoskeletal motors are _____.
____ and myosin have related structures and mechanisms, but different functions.
Vesicles and organelles can move on _____ and _____ have more than one kind of motor.
Molecular motors are the downstream targets of ______.
All three classes of cytoskeletal motors are ATPases.
KINESIN and myosin have related structures and mechanisms, but different functions.
Vesicles and organelles can move on MICROTUBULES and ACTIN FILAMENTS have more than one kind of motor.
Molecular motors are the downstream targets of SIGNALING CASCADES.
Most myosins have _ ___ chains, and _ __ chains.
- most are _ end directred
- globular ___ domain contains _____
- ____ domain is variable and contains ___ ____ for ____, and also binds to ___ or ____.
Most myosins have TWO HEAVY chains, and TWO LIGHT chains.
- most are PLUS end directred
- globular HEAD domain contains ATPASE
- TAIL domain is variable and contains COILED-COIL for DIMERIZATION, and also binds to MEMBRANE or TARGET VEISCLE.
Kinesins are ____ than myosin, most _ end directed. The head domain has ____, which is structurally related to ___ and _____. Head domain also has ____ binding site.
If motor is on _ terminus, it’s + end directed.
If motor is on _ terminus, it’s - end directed.
Neck region determines ____
Stalk region is where ____ is located, and allows for _____
Tail region binds to ____, it’s variable. Also binds ____.
Kinesins are SMALLER than myosin, most + end directed. The head domain has ATPASE, which is structurally related to MYOSIN and G-PROTEIN. Head domain also has MICROTUBULE binding site.
If motor is on N terminus, it’s + end directed.
If motor is on C terminus, it’s - end directed.
Neck region determines POLARITY
Stalk region is where COILED COIL is located, and allows for DIMERIAZTION
Tail region binds to TARGET, it’s variable. Also binds LIGHT CHAINS.
Dynein is _ end directed motor.
It’s a ____ protein.
-Found in ____/____ arms necessary for _____.
Functions in: ____ transport, ____, transport of ____, ___, ____.
-tail binds ____ or _____.
Dynein associated disease:
_____, causes ____ and ____
-occurs when dynein is _____ in mutant.
-mutation is specifically in __________
Dynein is MINUS end directed motor.
It’s a HUGE protein.
-Found in CILIA/FLAGELLA arms necessary for BEATING.
Functions in: RETROGRADE transport, MITOSIS, transport of MRNA,VESICLES, ORGANELLES, VIRUSES.
-tail binds CARGO or ANOTHER MICROTUBULE.
Dynein associated disease:
PCD/KARTAGENER SYNDROME, causes RESPIRATORY TRACT INFECTIONS and MALE INFERTILITY
-occurs when dynein is MISLOCALIZED in mutant.
-mutation is specifically in OUTER ARM CILIARY DYNEIN HEAVY CHAIN
How do cytoskeletal motors work?
- Binding and/or hydrolysis of ___ causes conformational change in motor.
- Rate limiting step is _______ following ____.
- Binding to ___ or ____ accelerates the rate limiting step.
- Can think of the cytoskeletal elements as ______.
How do cytoskeletal motors work?
- Binding and/or hydrolysis of ATP causes conformational change in motor.
- Rate limiting step is PRODUCT RELEASE following HYDROLYSIS.
- Binding to ACTIN or MICROTUBULE accelerates the rate limiting step.
- Can think of the cytoskeletal elements as NUCLEOTIDE EXCHANGE FACTORS.
Steps of Myosin II Movement
- Binding of ATP causes _____ and _____ before ____
- ____ release is the rate limitng step; it’s accelerated by binding ____
- Rate of myosin ____ determines speed.
Depletion of ____ results in attachment, _____ in muscle.
With each __ ____, myosin moves __ actin subunit closer to the ___ end of the filament.
Steps of Myosin II Movement
- Binding of ATP causes RELEASE and CONFORMATIONAL before HYDROLYSIS.
- PI release is the rate limitng step; it’s accelerated by binding ACTIN
- Rate of myosin ATPASE determines speed.
Depletion of ATP results in attachment, RIGOR MORTIS in muscle.
With each POWER STROKE, myosin moves ONE actin subunit closer to the PLUS end of the filament.
Kinesin Translation into Motion
- Trailing ____ weakly associated with MT
- ___ binds leading ____, and trailing ____ rotates
- New trailing _____ hydrolyzes ____. New leading ___ binds MT and dissociates _____.
- __ dissociates from trailing ____, weakening ____ binding to MT.
Kinesin Translation into Motion
- Trailing HEAD weakly associated with MT
- ATP binds leading HEAD, and trailing HEAD rotates
- New trailing HEAD hydrolyzes ATP. New leading HEAD binds MT and dissociates ADP.
- PI dissociates from trailing HEAD, weakening HEAD’S binding to MT.
Examples of Myosins:
Myosin I: ____ headed. Tail can bind ____. In ______, the actin filaments are oriented so the __ end points to ___ of microvillus.
Myosin II: form ____ filaments, as in ____, contractile ____, stress ___, and adhesion ____. Allows for ____, as in ____ filaments.
Myosin V: carries _____ on tail, walks towards _ end. Designed for ____ range transport. _____, ____ steps than other myosins.
Examples of Myosins:
Myosin I: SINGLE headed. Tail can bind PM. In MICROVILLI, the actin filaments are oriented so the PLUS end points to THE TIP of microvillus.
Myosin II: form BIPOLAR filaments, as in MUSCLE, contractile RING, stress FIBERS, and adhesion BELTS. Allows for CONTRACTION, as in SLIDING filaments.
Myosin V: carries CARGO on tail, walks towards PLUS end. Designed for LONG range transport. PROCESSIVE, LONGER steps than other myosins.
Transport of melanosomes
-Transported on ____ and ____ to the periphery of the cell where they are taken up by _____. _____ is required for transport to the _____.
______ tail binds cargo via _____ and ______, which binds to receptor on the melanosome cargo.
These ______ target ____ to specific intracellular membranes.
Mutations in ____, _____, or ____ cause Griscelli type 1 and Elejalde syndromes, which is characterized by _____, ____, and _____.
Transport of melanosomes
-Transported on MICROTUBLES and ACTIN to the periphery of the cell where they are taken up by KERATINOCYTES. MYOSIN V is required for transport to the _____.
MYOSIN V tail binds cargo via MELANOPHILIN and RAB27AGTP, which binds to receptor on the melanosome cargo.
These RAB GTPASES target MYOSINS to specific intracellular membranes.
Mutations in MYOSIN V, MELANOPHILIN, or RAB27A cause Griscelli type 1 and Elejalde syndromes, which is characterized by SILVERY HAIR, LIGHT SKIN IN DARK-SKINNED CHILD, and SEVERE NEUROLOGICAL DEFECTS.
