Neuron specific paralog of Microtubule Associated Protein 6 (MAP6) induces the formation of microtubule doublets indicating the role in neur

Microtubules play crucial roles in cellular processes. They alternate between phases of growth and shrinkage, described as dynamic instability essential to their activity. In neurons, dynamic and stable microtubules co-exist but the mechanisms underlying this stability still remain unclear. Recently, MAP6 was described as the first mammalian neuronal microtubule intraluminal protein that confers strong stability to microtubules. Based on sequence similarities, we identified the neuronal specific paralog of MAP6 which is MAP6d1. We found that MAP6d1 promotes rescues and reduces growth/shrinkage rates leading to the microtubules entering the pause phase. Surprisingly, MAP6d1 is also directly involved in the formation of microtubule doublets. As MAP6d1 is exclusively present in the neurons with motile cilia whose cytoskeletal arrangement includes microtubule doublets. Our objective is to solve the structure of MAP6d1 induced-microtubule doublets using cryo-electron tomography.