Motor Proteins- Kinesin

Description

Structural Basis for Biological Function (Molecular Motors) Flashcards on Motor Proteins- Kinesin, created by gina_evans0312 on 15/12/2013.
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Flashcards by gina_evans0312, updated more than 1 year ago
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Created by gina_evans0312 almost 11 years ago
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Resource summary

Question Answer
Reason for Cellular Transporters Diffusion is too slow for the cell to rely on it
Role of Transport Proteins For direct, organised and regulated transport
Giant Squid Axon Where motor proteins were first found
Anteriograde transport Towards axon
Retrograde transport Towards cell body
ATP Required for continued transport
Protein that makes up microtubules Tubulin- made of alpha/beta dimers
Distance between each motor protein binding site 8nm
Size of microtubules 13 protofilament tracks
+ve end of microtubule Where tubulin is added
-ve end of microtubule Where tubulin is removed
Microtubule ATP requirement For microfilament assembly
No of Kinesin types in cell 50
Kinesin
Kinesin Superfamily G-Protein
Direction of Kinesin movement From minus end to plus end
Structure of Kinesin 1- Chains 2 light (70kDa) and 2 heavy (120kDa)
Design of Kinesin 1 - Cargo binding Near C terminus
Design of Kinesin 1 - Stalk Coiled coil structure, connecting cargo and microtubule binding sites
Design of Kinesin 1 - Microtubule binding sites N terminus- 2 NTPase head motors
Design of Kinesin 1 - Neck Linkers Connect NTPase heads to coiled coil stalk
Role of Neck linker For power stroke
Role of coiled coil stalk Connectivity and control
Sliding assay Bind protein to glass, and see if it can move free microtubule
Rate of Kinesin movement 800nm/second
Processive movement Movement that can only occur by following a strict process
Monomeric heavy chain kinesin mutants Slow and non-processive
Potential Models for movement of Kinesin Inchworm and Hand Over Hand models
Optical Trap Use latex bead as cargo and use this method to measure it's movement
Inchworm Model First head moves, second one catches up in 8nm steps
Hand Over Hand model Each head moves 16nm- leading and trailing heads swap over
Determining Kinesin Movement Method Label one head of Kinesin with a fluorophore and see how far it moves
Precision of Fluorophore Method 1nm
Shows long lived, non moving stable state and 16nm steps
Role of Switch's I & II Detect presence of terminal (gamma) phosphate of ATP
Movement of Switch II A spring loaded gate moving in/out in response to gamma phosphate
ATP Binds to sensor Engaging it- phosphate release, releases sensor
ATP binding & sensor relationship ATP binding engages sensor and vice versa
Relay Helix Relays movement of Switch II around the protein
Conformational changes of ATP binding Neck linker and tubular binding domain
12 amino acid loop Binds kinesin to tubulin
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