PKA-dependent phosphorylation of IP3K-A at Ser119 regulates a binding affinity with EB3.

Microtubule-associated end-binding protein 3 (EB3) accumulates asymmetrically at the tip-end of growing microtubules, providing a central platform for linking various cellular components. EB3 orchestrates microtubule dynamics and targeting, enabling diverse processes within neurons. Inositol 1, 4, 5-trisphosphate 3-kinase A (IP3K-A; also known as ITPKA) is a neuron-enriched protein that binds to microtubules by PKA-dependent manners. In this study, we found that IP3K-A binds to EB3 and their binding affinity is precisely regulated by protein kinase A (PKA)-dependent phosphorylation of IP3K-A at Ser119 (pSer119). We also revealed that the complex of IP3K-A and EB3 dissociates and reassociates rapidly during chemically induced LTP (cLTP) condition. This dynamic rearrangement of IP3K-A and EB3 complex will contribute remodeling of microtubule cytoskeleton allowing effective structural plasticity in response to synaptic stimulations.