Item

Abstract

With the advent of focused ion beam milling and direct detectors, in situ cryo-electron tomography set off on a journey to explore structures deep within the cell. This thesis contributes to a daring vision of
the future that in situ research can take: Visual Proteomics, a comprehensive
molecular atlas of the cell. With the technical foundation laid,
incremental steps towards Visual Proteomics were taken in three detailed
analyses of the green alga Chlamydomonas, testing the potential
of (1) reaching functional conclusions by combining structural and positional
information, (2) understanding a process through a structural
interactome and (3) making new discoveries by structural analyses
of hitherto unknown complexes. The respective results included the
(1) identification of a nuclear degradation hub around nuclear pore
complexes composed of structurally tethered proteasomes, (2) localization
of ER-associated degradation in non-membrane bound microcompartments
of densely clustered proteasomes at the ER membrane
and (3) structural description of trans-luminal protein arrays that link
the central cisternae of the Golgi together. Concluding, there is a discussion
of current advancements and required future developments
towards the realization of Visual Proteomics.