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Poly(ADP-ribosyl)ation (PARylation) is a dynamic protein modification, the control of which is important for diverse cell biological processes and normal physiology. Common mechanistic themes are being characterized by which PARylation alters the functions of target proteins, and the PAR-binding modules that mediate this.
The centriole is crucial for the formation of flagella, cilia and centrosomes. The ultrastructure of the centriole reveals a striking ninefold radial arrangement of microtubules. Emerging insights into the molecular mechanisms of centriole assembly include the function of spindle assembly abnormal 6 (SAS-6) proteins in imparting the ninefold symmetry.
Chromatin compaction has profound implications for the regulation of transcription, replication and DNA repair. Changes in nucleosome structure and stability — due to the incorporation of variant histones and post-translational modifications of histones — affect chromatin compaction. Chromatin structures are not nearly as uniform as previously assumed, which should be taken into account in the context of specific biological functions.
Approximately half of human proteins are glycosylated, and the resulting diverse glycan patterns encode an additional level of information. The process of protein glycosylation is mediated by numerous enzymes with dynamic localization, regulation and specificity. High-throughput techniques facilitate the study of complex protein glycans and may give further insights into their roles in protein homeostasis, cell signalling and cell adhesion.
Membrane trafficking relies on changes in membrane identity, which are determined by RAB GTPases and phosphoinositides. Coordinated regulation of RABs and phosphoinositides, which is achieved by direct physical and functional interactions between their regulatory enzymes, is emerging as a central mechanism to ensure membrane trafficking fidelity.
Six scientists in the field of stem cell research comment on our basic understanding of stem cells and other pluripotent cells, on their potential therapeutic use and on key challenges that remain.