Tubulin is an essential building block of postsynaptic density

The presence and roles of tubulin in and around the postsynaptic density (PSD) has long been a point of debate, despite the identification of tubulin immunoreactivity in the PSD as early as 1975. In our previous paper (Suzuki et al., 2021, Life Science Alliance, 4; e202000945) we have suggested a fundamental role for tubulin in the structure of the postsynaptic density (PSD) at excitatory synapses based on our experiments on PSD lattice (PSDL), which is an backbone structure for PSD. This investigation extends our prior exploration of the PSDL, and unveils a hitherto unrecognized characteristic of tubulin within the PSD. We identified PSDL-like meshwork structures and their connection to microtubules in the purified tubulin sample (purity, >99%). This result suggests the possibility that PSDL structure is constructed by tubulin alone. Furthermore, we found unique dysintegration of PSDL and PSD structures. The details of this decomposition will be provided in the meeting and discussed. These results strengthen the idea that tubulin is a fundamental building block of PSD architecture and that tubulin has the potential to form unique structures distinct from traditional microtubules in the postsynaptic region. In summary, together with our previous report that PSDL’s capacity to interact with polymerizing microtubules, this investigation suggests the involvement of tubulin in the PSD and PSDL in the construction and function (synaptic plasticity) of PSD.