TMT spectrometry unveils key M6a interactors

Abstract

The membrane glycoprotein M6a -together with proteolipid protein (PLP), DM20 and M6b- belongs to the tetraspan PLP family. M6a is a neuronal surface protein that promotes neuronal stem cell differentiation, migration, neurite and axonal outgrowth, filopodia/spine induction and synapse formation in primary neuronal cultures and non-neuronal cell lines. M6a has two extracellular loops (EC1 and EC2). four transmembrane domains, one intracellular loop and the N and C terminus facing the cell cytoplasm. However, the complete mechanism of action or proteins associated with it through its extracellular loops remained unknown. In previous work we provided strong evidence that M6a´s extracellular loops widely contribute to its function. To asses this question, we designed and purified a chimera protein (M6a-loops as a bait protein) which was subjected to co-immunoprecipitation (Co-Ip) with rat hippocampi homogenates followed by TMT-MS. The TMT-MS and data analysis was done by the Proteomics Core Facility from the European Molecular Biology Laboratory (EMBL, Heidelberg, Germany).