This group is working to develop and deploy nanodroplet sample preparation (nanoPOTS) mass spectrometry (MS) at the top-down, i.e. proteoform-level, to enable characterization of proteoforms in tissue sections with near single cell resolution. To increase the resolution from thousands of cells to near single cell, advanced MS imaging (MSI) approaches are utilized. MSI data will be cross-referenced with global proteomics data obtained via microscale top-down MS of microdissected tissue regions. The UG3 phase efforts will be focused on histones and the kidney as a development platform and leverages a unique combination of microscale top-down LCMS, MSI and novel image processing and visualization tools. In the UH3 phase, the team will construct comprehensive proteoform-specific maps of multiple tissue types and facilitate multimodal molecular mapping of specific functional units of the kidney by leveraging the HubMAP Consortium ongoing efforts. Successful completion of this research will allow for comprehensive characterization of the full spectrum of proteoforms in tissues and cells thus addressing an important and under- studied area of biology and critical gap in HuBMAP efforts.