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RAS proteins are monomeric GTPases that act as binary molecular switches to regulate a wide range of cellular processes. Their trafficking and activity are regulated by constitutive post-translational modifications (PTMs), including farnesylation, methylation and palmitoylation, as well as conditional PTMs, such as phosphorylation, peptidyl-proly isomerization, ubiquitylation, nitrosylation, ADP ribosylation and glucosylation.
Bone homeostasis depends on the opposing activities of osteoblasts (which form bone) and osteoclasts (which destroy bone). Recent studies have revealed the transcription factors (for example, RUNX2 and osterix) and developmental signalling pathways (including WNT and Notch signalling) that regulate the differentiation and function of osteoblasts.
Satellite cells are a heterogeneous population of stem and progenitor cells with crucial roles in muscle repair and regeneration. Although paired-box 7 (PAX7) is necessary to maintain the undifferentiated stem cell state, a requirement for PAX7 in adult satellite cells was recently challenged and remains controversial.
The autophagosome, the central organelle in macroautophagy, is constructed from a membrane template called the phagophore, to which autophagy-related (ATG) proteins are hierarchically recruited. Recent findings suggest that non-canonical autophagy may also occur in the absence of these key autophagy proteins.
Cells use molecular motors to position and segregate organelles. Recent studies show that class V myosins function as actin-based cargo transporters in yeast, moving the vacuole, peroxisomes and secretory vesicles. There is also increasing evidence in vertebrate cells that class V myosins can serve as short-range, point-to-point organelle transporters rather than just tethering organelles to actin.