cell biology protein · BEGINNER LESSON
EB3
EB3 is a microtubule plus-end tracking protein that marks growing microtubule tips. It helps connect microtubule growth to other cell processes such as actin organization, calcium signaling, and cell shape change.
What EB3 is
EB3 is a protein that rides at the plus-end of microtubules, the fast-growing end of these cell skeleton fibers. A plus-end tracking protein, or +TIP, is a protein that concentrates at growing microtubule ends. In the sources, EB3 is described as autonomously marking growing ends and as a scaffold that helps organize other proteins at those tips. It is also called MAPRE3 in one source. [0,2]
[1] MAPRE3 — Affinage [3] EB3 Regulates Microtubule Dynamics at the Cell Cortex and Is Required for Myoblast Elongation and Fusion
How EB3 works
EB3 does not just sit on microtubules; it helps recruit partner proteins to the tip. One source says it binds CLIP-170 and CLIP-115 through a C-terminal tyrosine residue and changes how long they stay at tips. It can also bring the catastrophe factor MCAK to growing ends. In another study, EB3 directly bound the S/TxIP motif in the inositol 1,4,5-trisphosphate receptor 3 (IP3R3), helping these receptors cluster so calcium signals can occur at endothelial cell microtubule tips. [0,1]
[1] MAPRE3 — Affinage [2] Microtubule-Associated Protein EB3 Regulates IP3 Receptor ...
What EB3 affects in cells
The sources connect EB3 to several cell behaviors. In muscle precursor cells, EB3 was required for elongation, microtubule capture at the cell cortex, and fusion into myotubes, while EB1 could not fully replace it. In endothelial cells, EB3 helped organize IP3 receptors into signaling clusters, and this was needed for calcium-dependent signaling and increased permeability after inflammatory stimulation. EB3 also changes during cell division: Aurora A and Aurora B phosphorylation at Ser-176 stabilizes it in mitosis, while SIAH-1 normally promotes its degradation. [0,1,2]
[1] MAPRE3 — Affinage [2] Microtubule-Associated Protein EB3 Regulates IP3 Receptor ... [3] EB3 Regulates Microtubule Dynamics at the Cell Cortex and Is Required for Myoblast Elongation and Fusion
Limitations and open questions
The sources note that EB3 can overlap with EB1 in some microtubule functions, so not every role is unique. They also point out unresolved details such as the molecular basis of end recognition and how EB3 and EB1 differ in all contexts. Some findings are context-specific: EB3 behavior depends on the cell type, the binding partner, and the signaling state of the cell. [0,2]
[1] MAPRE3 — Affinage [3] EB3 Regulates Microtubule Dynamics at the Cell Cortex and Is Required for Myoblast Elongation and Fusion
SEE THE IDEA
EB3 at growing microtubule ends
The fast-growing tip where EB3 accumulates.
Marks the tip and acts as a scaffold for partner proteins.
Examples include CLIP-170/CLIP-115, MCAK, and IP3R3.
Tip organization can affect microtubule dynamics, calcium signaling, and cell shape.
EB3 localizes to the growing tip, recruits or organizes partners there, and this changes how the microtubule tip behaves and how the cell responds.
EB3 is a tip-associated organizer, not just a passive marker.
TRY IT YOURSELF
Test your understanding
Choose an answer, then check the explanation.
PUT IT TOGETHER
Match each concept to its meaning
Drag a label onto its description, or select a label and then select a description. This also works with a keyboard.
4 pairs to match
Sources and further reading
This general lesson was generated from public source material. It explains a concept; it does not interpret a private paper or provide medical advice.