GAI and RGA proteins normally act as repressors of gibberellin responses. Gibberellin acts indirectly through an unidentified signaling intermediate, which is thought to bind to the regulatory domains of the GAI and RGA Proteins. 

TLS Online TPP Program

#Id: 1539

#Unit 2. Cellular Organization

Class IV IF proteins compose the neurofilaments found in neurons

TLS Online TPP Program

#Id: 1540

#Unit 2. Cellular Organization

Kinesin-13 (End-Binding Proteins)

• A member of the kinesin motor protein superfamily

• These proteins are ATPases

 

TLS Online TPP Program

#Id: 1541

#Unit 2. Cellular Organization

Kinesin-13 (End-Binding Proteins)

• Bind and curve the end of the tubulin protofilaments into the GDP-β-tubulin conformation

• Facilitate the removal of terminal tubulin dimers 

• Greatly enhancing the frequency of catastrophes

TLS Online TPP Program

#Id: 1542

#Unit 2. Cellular Organization

Op18/stathmin (End-Binding Proteins) binds selectively to curved protofilaments and enhances terminal tubulin heterodimer dissociation from a microtubule end. 

 

TLS Online TPP Program

#Id: 1543

#Unit 2. Cellular Organization

Stathmin decreases the effective concentration of tubulin subunits that are available for polymerization (an action analogous to the drug colchicine) and enhances that a growing microtubule will switch to the shrinking state.

TLS Online TPP Program

#Id: 1544

#Unit 2. Cellular Organization

Phosphorylation of stathmin inhibits its binding to tubulin.