Proteine und Kapitel 18

-Binds to tubulin dimers so they cannot polymerize into microtubules

=> resulting in a loss of dynamic microtubules, but not the additionally stable centrosomes

Also bind tubulin dimers and restrain them from forming polymers

stabilizes microtubules against depolymerization

=> inhibits cells from dividing

Tau

-neuronal protein in dendrites

-stabilizes microtubules and links them to intermediate filaments

MAP2

-neuronal protein in dendrites

-forms cross bridges between microtubules and links them to intermediate filaments

MAP4

-not present in neurons

activity of MAPs is controlled by phosphorylation

phosphorylated MAPs cannot bind microtubules

=> phosphorlyation promotes microtubule disassembly

-MAPs associated with the + end of microtubules

(plus end tracking proteins)

-best studied ones are EB1 and EB3

-another function is to link the + end to other structures or membranes

associates with the microtubule tip containing GDP-Pi-Tubulin

-binding induces a twist in the tubulin subunits transmitting a long range signal to enhance GTP hydrolysis

=> destabilizer of microtubules

EB1 is also recruited by many other +TIPs

-can bind free alpha-beta-tubulin dimers aswell as the gently curved regions in protofilaments

-increases the effective alpha-beta-tubulin concentration to enhance assembly

bind to gently curved ends and supress catastrophes

destabilizes microtubules