Wordlists for Exam 3
Lectures 29 & 30 - Cytoskeleton & Actin

microfilaments (MFs) = actin filaments (AFs)
(+) end, (-) end
thymosin
profilin
capping proteins
tropomyosin
cofilin
Arp = Actin-related proteins
Arp2/3 complex

Sarcomere:
Z disc + half I band, A band, half I band+ Z-disc

"Thin Filaments" of actin = 7-8 nm filaments
"Thick Filaments" = myosin II filaments
Myosins = actin filament "motor proteins"

Globular heads are actin-stimulated ATPases.

Myosin molecules have several protein chains:

heavy chains (2 heavy chains in all but 2 of 18 myosin classes)
light chains (LCs)

calmodulin (CaM) for all but myosin II
Myosin II LCs are evolutionary derivatives (homologs) of CaM

"essential"
regulatory
regulate contraction of smooth muscle and non-muscle, but not striated muscle

Light chain kinase

rigor complex
 
(+) ends of actin filaments at Z discs
Myosin II heads "walk" toward the (+) ends of AFs.
Myosin II is a "(+) end" actin motor.

stress fiber
minisarcomere
contractile bundles - alpha-actinin (bundles with 40 nm MF spacing)
contractile bundles
actin filaments attached to intermediate junction (adhesion belt) in epithelia
contractile ring (e.g., cleavage furrow)
stress fibers attached to focal adhesions

In focal adhesions, integrin "grips" fibronectin in extracellular matrix.


Myosin LC kinase activates non-muscle myosin II filament formation.

parallel bundles - fimbrin (bundles with 10 nm MF spacing)
"core microfilaments" = parallel bundles
villin
mysoin I
non-filamentous myosins:
myosin I (single head) - membrane tension on MFs
Vesicle movement

myosin V (2 heads)
myosin VI (2 heads) is a (-) end actin motor protein
leading edge
parallel bundles of AFs - filopodium (plural: filopodia)
actin gels

lamellipodium (plural: lamellipodia) - slowly migrating cells

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