Module 5 Flashcards
Bind to actin filament –> allows movement
Actin-Binding Motor Proteins
Actin filaments linked to NON ACTION structural proteins
Membrane Anchors
side-to-side linkage –> form actin filaments
Cross-linking proteins
Bind to actin polymer –> sever/ induce disassembly
Severing & Depolymerizing
Bind to + or - end –> stabilizing polymer –> prevents disassembly/further assembly
Capping protein
Bind to actin polymer –> increase stability, allowing new branch growth
Nucleating protein
Bind to actin filament –> allows movement
Actin-Binding Motor Proteins
Domains of Motor Proteins
Motor, regulatory, tail
Motor Domain
-1 heavy chain
-binds to ATP and actin filaments
Regulatory Domain
-1 heavy, 2 light chains
-Moves back and forth as myosin moves along actin filament
Tail Domain
Binds to other cellular proteins OR other myosins
Movement of Actin binding motor proteins
- HYDROLYSIS
ATP –> ADP + Pi causes conformational shift swinging the domain - ACTIN BINDING
motor domain +actin filament –> releases Pi causes conformational change pulling myosin along actin filament
ADP released –> binding of new ATP –> myosin unbinds from actin filament
- MOVEMENT
Moves towards + (barbed) end
Actin Filaments responsible for migration
Filopodia
Lamellipodia
Stress Fibre
Filopdia
-thin
-parallel
“+” faces membrane
-extends in direction of intended movement
Lamellipodia
-larger
-sheet-like bundles of actin filament
-polar (+ end faces membrane)
-form broader structures
Stress Fibres
-form around interns
-resemble filopodia BUT
“+” end faces cytosol
-rich in MOTOR proteins (move cell forward)
Cyclin
Proteins associated with progression of cell cycle
CDKs
bind to cyclin to ACTIVATE and TRIGGER next stage of cell cycle
p53
tumour suppressor protein (prevents division and uncontrollable replication)
initiates APOPTOSIS in damaged DNA of cells
Mitosis Phases
Prophase
Prometaphase
Metaphase
Anaphase
Telophase
Before Mitosis
INTERPHASE
-growing/preparing for division
-DNA replication occurs
After Mitosis
CYTOKINESIS
-in mammalian cells contractile ring forms (cleavage furrow) splitting into 2 identical daughter cells
The cell cycle
Mitotic Spindle Checkpoint
G1 Phase
G0 Phase
G1/S Phase
S Phase
S/G2 Checkpoint
G2 Phase
G2/M Checkpoint
M Phase
