Cytoskeleton Acessory Proteins and Motor Proteins

Thymosin

Interacts with G actin, blocks and binds to the ATP site of G actin preventing incorporation of a G actin to a filament

Profilin

Binds to G actin in a way that allows it to perfectly bind to the growing filament (barbed end)

NPF

Has a domain that interacts with plasma membrane creates branched actin networks

Formin

Creates straight actin networks bound to plasma membrane

Formin dimer

Bind to the barbed end and alter their confirmation to create better molecular complementarity for faster incorporation of monomers

ARP 2/3

Seven protein complex that inserts into an actin network at a 70 degree angle; creates a new nucleation point. This new nucleation point extends into whichever direction leading to a branched network

Cofilin

Binds intensely to the ADP rich parts of the actin filament laterally, so intense it breaks bonds and creates new - ends for rapid dissociation

Gelsolin

Requires calcium to bind to actin filaments laterally. It physically inserts itself between monomers to break them apart, remains bound to the + end

Tropomyosin

Binds to act in laterally and stabilizes filament

Fimbrin

Closely associates actin together

Alpha actin

Loosely packs actin together

Myosin 2

Muscle contraction (towards + end)

Myosin 5

Carries organelles (towards + end)

Myosin 6

Organelle movement/anchoring, actin filament organization (towards – end)

Stathmin

Binds 2 dimers in a way that blocks them from incorporating on the fast growing end

• tips

Increase the speed of polymerization by guiding dimers onto the + end of the protofilament

XMAP215

Physically interacts with dimers influencing them to incorporate faster to the + end

Kinesin-13

Binds directly to GTP rich regions (engages with beta tubulin), its motor activity pulls them apart causes loss of GTP cap and catastrophe

Augmin

Single protein that binds into an existing microtubule laterally, creates space for additional proteins to interact with gamma tubulin, creating an MTOC off a pre-existing microtubule

MAP2/Tau

Physically bind to protofilament to stabilize, arm associates with another microtubule, laterally stabilize and crosslink

Katanin

Binds onto a free C terminal tail of tubulin, winds it physically through their structure, shoves into the microtubules, dislodging alpha and beta tubulins, break structure and depolymerize by creating many – ends

Kinesin 1

Organelle transport

Kinesin 5

Shift microtubules against each other

Kinesin 14

Moves toward – end