KINE 1000 Lecture Notes - Lecture 3: Mitosis, Hydrolysis, Cell Migration
4 Jun 2018
School
Department
Course
Professor
Chapter 6 – Part
Two Types of Motor Proteins Move Along Microtubules – Kinesins & Dynein
• Like actin filaments, microtubules use motor proteins to transport cargo
• Two Major Class of Microtubule-based motor:
1. Kinesin
2. Dynein
Kinesin
• Moves along microtubules
• Kinesin has motor domains & coiled-coil tails
• Most walk towards plus end, some walk toward minus
end
• Tails have binding sites for organelles or microtubules
• Kinesin are able to carry organelles, slide on microtubules & formation of
mitotic spindle
• Kinesin-1 carriers organelles away from cell body to axon terminal by
walking towards plus end of microtubules
• Kinesin-1 has two heavy chains per active motor, 2 globular head motor
domains held together by an elongated coiled-coil tail that is responsible
for heavy-chain dimerization
• Kinesin-1 light chain associates w/ each heavy chain through its tail domain
& mediates cargo binding.
• Motor domains at N-terminal of heavy chains, C-terminal forms tail that
attaches to cargo like membrane-enclosed organelles.
• Kinesin-14 moves towards minus end of microtubule
Kinesin Cycle
1. Front head w/ADP loosely bound to microtubule. Rear end tightly bound
w/ATP
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Two types of motor proteins move along microtubules kinesins & dynein: like actin filaments, microtubules use motor proteins to transport cargo, two major class of microtubule-based motor, kinesin, dynein. & mediates cargo binding: motor domains at n-terminal of heavy chains, c-terminal forms tail that attaches to cargo like membrane-enclosed organelles, kinesin-14 moves towards minus end of microtubule. Kinesin cycle: front head w/adp loosely bound to microtubule. Rear end tightly bound w/atp: front head loses adp, binds to atp which binds tight to tubulin. Rear head hydrolyzes atp which binds loosely to tubulin: conformational change in linker throws rear head forward loose binding to tubulin. Movement is in linker b/t head & tail. Movement is processive= walks along microtubule, never lets go. Mechanochemical cycle of kinesin: kinesin-1 is dimer of 2 nucleotide-binding motor domains (heads) connected through long coiled-coil tail, at start, one of motor domains, the rear/lagging head, is tightly bound to microtubule w/atp.
