Tau dephosphorylation at tau-1 site correlates with its association to cell membrane

It has been considered that tau protein is mainly a cytoplasmic protein sin ce it is a microtubule associated protein, However, it has also been sugges ted that tau could be located in the cell nucleus and membrane. In our work , the cellular distribution of tau has been studied by immunofluorescence a nd western blot analysis, after subcellular fractionation in neuroblastoma cells and in tau-transfected non neural cells using, mainly, two types of t au antibodies; antibody 7.51 (that recognizes tau independent of its phosph orylation level); and antibody Tau-1 (that recognizes tau only in its depho sphorylated form). Also, tau was expressed in COS-1 cells to test for the f eatures involved in the sorting of tau to different cell localizations. Our results show that tau associated to cell membrane has a lower phosphorylat ion level in its proline-rich region. Additionally, in differentiated neuro blastoma cells, tau phosphorylation, at that region, decreases and the amou nt of tau associated to cell membrane increases.