Mammalian end binding proteins control persistent microtubule growth

Area of Science:

• Cell Biology
• Molecular Biology
• Biochemistry

Background:

• End binding proteins (EBs) are essential for microtubule dynamics.
• EBs form networks at microtubule plus-ends, regulating growth and stability.

Purpose of the Study:

• Investigate the roles of mammalian EBs (EB1, EB2, EB3) in microtubule dynamics.
• Analyze the specific protein domains responsible for EB function and localization.

Main Methods:

• Utilized protein depletion and rescue experiments in cellular models.
• Performed in vitro reconstitution assays with purified tubulin and EBs.
• Analyzed domain-specific functions and dimerization requirements.

Main Results:

• EB1 and EB3, but not EB2, were found to promote persistent microtubule growth by suppressing catastrophes.
• EB plus-end tracking is dependent on the calponin homology domain but not dimer formation.
• Dimerization is essential for the anti-catastrophe activity of EBs within cells.
• In vitro, EBs promoted catastrophes, suggesting cellular context involves counteracting other regulators.

Conclusions:

• Mammalian EBs play distinct roles in microtubule dynamics, with EB1 and EB3 being key regulators of growth suppression.
• The calponin homology domain mediates EB plus-end tracking, while dimerization is crucial for their anti-catastrophe function in cells.
• Cellular EBs likely prevent microtubule catastrophes by interacting with other regulators at microtubule ends.