BI203 Lecture 19: Cytoskeleton - Microtubule Motors, Movement, and Intermediate Filaments Flashcards
____ and ____: Molecular motors that move along microtubules powered by ATP hydrolysis.
kinesins, dyneins
Most ____ move toward the plus end of microtubules = anterograde transport.
kinesins
Most kinesins move toward the ____ end of microtubules = anterograde transport.
plus
Most kinesins move toward the plus end of microtubules = ____ ____.
anterograde transport
Most ____ move towards the minus end = retrograde transport.
dyneins
Most dyneins move towards the ____ end = retrograde transport.
minus
Most dyneins move towards the minus end = ____ ____.
retrograde transport
A major role of microtubules is to transport ____, ____, and ____ through the cytoplasm.
macromolecules, vesicles, organelles
Different members of the kinesin and dynein families are thought to transport cargo in ____ directions.
opposite
____ ____ has two heavy chains and two light chains. The heavy chains have α-helical regions that form coiled-coils.
Kinesin 1
____ ____ (11 nm) are an intermediate between actin filaments (7 nm) and microtubules (25 nm).
intermediate filaments
Intermediate filaments play a structural role by providing ____ ____ as well as a ____ for intracellular signaling.
mechanical strength, scaffold
Intermediate filaments are not directly involved in cell movements, but provide mechanical strength and a scaffold for the localization of ____ ____.
cell processes
Intermediate filaments are ____ found in yeast, plants, and some insects.
NOT
Intermediate filaments are composed of many types of proteins expressed in different types of cells.
Type I and II are ____, in epithelial cells.
keratins
____, a type of intermediate filament, forms a network extending out from the nucleus toward the cell periphery.
Vimentin
____, a type of intermediate filament, is expressed in muscle cells where it connects the Z discs of individual contractile elements.
Desmin
____ (NF) ____ (with α-internexin) are the major intermediate filaments of many neurons; provide support for long axons.
neurofilament (NF) proteins
Due to anti-parallel organization, intermediate filaments are ____ (have no electrical polarity).
apolar
Most intermediate filaments can be ____ which regulates their assembly and disassembly (i.e. nuclear lamins).
phosphorylated
Intermediate filaments have a central α-helical rod domain which plays a central role in filament assembly.
The head and tail domains determine the specific functions.
The central rod domains of two polypeptides form a coiled coil.
The dimers associate in a staggered antiparallel fashion to form tetramers, which assemble end-to-end to form protofilaments.
____ protofilaments wind together to form an intermediate filament.
8
Intermediate filaments do NOT have distinct ends.
They are more stable and do ____ have the dynamic behavior of actin filaments or microtubules.
NOT
Intermediate filaments form a cytoplasmic ____ in most cells, extending from a ring around the nucleus to the plasma membrane.
They can also associate with other cytoskeleton elements, providing a scaffold that organizes the internal structure of the cell.
network
____ are molecular complexes of cell adhesion proteins and linking proteins that attach the cell surface adhesion proteins to intracellular ____ intermediate filaments.
desmosomes, keratin
