molecular motors lecture 33`bsci 420/421nov 18, 2002 “to survive the 21 st century, our thinking...
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Molecular Motors
Lecture 33 ` BSCI 420/421 Nov 18, 2002
“To survive the 21st century, our thinking must be creative and humane as well as analytical.”
- Robert Kuhn
1. Myosins2. Kinesins3. Dyneins
1. Myosins • Are a family of motor proteins that bind to & move along actin filaments toward the + ends.
• Large globular heads bind and split ATP
• Undergo a configurational change that changes the angle of the head with respect to an -helical tail. E.g. Myosin II
MT-based Motors: Kinesin & Dynein
Kinesin is a large protein with 4 polypeptide chains
Like myosin it has 2 heavy chains, each w a globular head domain and long -helical tail.
2 light chainson cargo-
MT binding endbinding (vary in diff.
cells w diff.cargo)
ATP-binding site Coiled-coilin each head tail
3. Dyneins are a family of minus end directed MT motors.Largest and fastest molecular motors (14 m/sec vs2 m/sec for kinesin)(fig 56)