Tubulin & Microtubules Flashcards

Flashcards covering key vocabulary and concepts related to tubulin, microtubules, and their dynamics.

Tubulin

A dimer of alpha and beta subunits that bind and hydrolyze GTP, forming microtubules.

Microtubules

Assembled from tubulin dimers, have (+) ends for net assembly and (usually anchored) minus, nucleating ends.

Dynamic Instability

A property of microtubules that can be regulated by other proteins.

Microtubule Organizing Centers (MTOCs)

Structures from which microtubules are assembled.

Centrosome

Consists of centrioles (MT-based), pericentriolar material, and gamma tubulin ring complexes.

Gamma Tubulin Ring Complex (y-TuRC)

Nucleates microtubule assembly and remains associated with the minus end.

GTP Cap

Presence or absence determines dynamic instability of microtubules.

Catastrophe

Rapid shrinkage of microtubules due to random loss of GTP cap.

Rescue

Regain of GTP cap leading to rapid growth of microtubules.

Microtubule Associated Proteins (MAPs)

Regulate microtubules; examples include stathmin, +TIPs, XMAP215, kinesin-13, katanin, tau, MAP2, and plectin.

Kinesin-13

A catastrophe factor that binds to microtubule ends and promotes depolymerization.

XMAP215

Stabilizes the end of a growing microtubule, binds tubulin dimers and delivers them to the microtubule plus end.

MAP2 & Tau

Wall-binding MAPs that stabilize microtubules by binding along their sides; involved in filament bundling and cross-linking.

Stathmin

Binds to tubulin heterodimers and prevents their addition to the + end, reducing the pool of free tubulin.

Katanin

An MT-severing protein composed of two subunits; hydrolyzes ATP and severs the microtubule.