MAPRE1, also known as EB1, is a core member of the end-binding (EB) family of microtubule plus-end tracking proteins that localizes to growing microtubule tips and functions as a scaffold that coordinates microtubule dynamics with spindle organization, intracellular transport, and cell polarization. The protein consists of an N-terminal calponin homology–like microtubule-binding domain, a central flexible linker, and a C-terminal coiled-coil dimerization domain that creates a four-helix bundle with a hydrophobic cavity; this C-terminal region mediates dimer formation and provides docking sites for multiple +TIPs that carry a conserved SxIP motif or CAP-Gly domains, including dynactin p150Glued, CLIPs, and other end-tracking regulators. Dimeric EB1 autonomously recognizes the GTP/GDP‑Pi tubulin cap at growing microtubule plus ends, accumulates there ahead of most other +TIPs, and promotes persistent microtubule growth and rescue by stabilizing the end structure, while its C-terminal tail recruits and organizes a constellation of effector +TIPs whose activities modulate catastrophe frequency, lateral interactions within K‑fibers, and coupling of microtubule plus ends to kinetochores, the cell cortex, and organelles. Each EB1 monomer presents distinct binding surfaces for CAP-Gly and SxIP-containing partners, and the flexible tail exerts an autoinhibitory effect on EB1’s microtubule-polymerizing activity, which is relieved when p150Glued or other partners engage the tail, indicating an allosteric mechanism by which cargo binding enhances EB1’s ability to promote microtubule assembly. Acute disruption of EB1–+TIP complexes at microtubule ends rapidly attenuates microtubule growth, alters local growth directionality, and is sufficient to reorient migrating cancer cells, underscoring EB1’s central role in translating +TIP complexes into spatially controlled microtubule dynamics that support directed motility and polarity. EB1 also contributes to the organization and function of noncentrosomal microtubules by forming a regulatory module with CAMSAP2 and Golgi-associated AKAP9/PDE4DIP complexes, which tethers CAMSAP2-decorated minus-end-stabilized microtubules to the Golgi and facilitates efficient retrograde transport of autophagosomes along these tracks, linking EB1 activity at plus ends with minus-end organization and autophagy-related trafficking. MAPRE1/EB1 acts as a structurally defined dimeric plus-end adaptor that binds and stabilizes GTP‑tubulin caps, recruits SxIP and CAP-Gly +TIPs, and coordinates centrosomal and noncentrosomal microtubule arrays with chromosome segregation, polarized migration, and autophagosome transport.
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