Principles of Cellular Compartmentalisation

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Eukaryotic cells contain membrane-bounded organelles to separate distinct cellular
functions. Nevertheless, the organelles need to communicate with each other and the
extracellular space. Specialized domains on organelles and the plasma membrane support
communication through at least three different ways: 1) transport vesicles that are formed
at a donor compartment -exit site- and fuse with and are consumed at a specific target
compartment -arrival site- 2) transport containers/organelles that briefly fuse with each
other, yet maintain their overall identity; a mechanism referred to as ‘kiss-and-run’ or 3)
membrane contact sites at which two compartments come into very close contact that
allows exchange of lipids and ions between organelles or organelles and the plasma
membrane. Key regulators of these specialized compartments are small GTPases of the Arf
and Rab families. In their activated, GTP-bound state, they recruit effector molecules, which
locally change the membrane and protein environment and thus give raise to specialized
compartments. These small GTPases are regulated themselves through the action of GEFs
and GAPs allowing for the tightly temporal and spatial control of GTPase activity and hence
membrane compartmentalization. Compartmentalization is not restricted to membranes
but takes also place in the nucleus and the cytoplasm, where membrane-less condensates
are formed to fulfill dedicated functions. For example, under stress, processing bodies and
stress granules form in the cytoplasm and degrade or store RNA. When stress subsides, they
can be turned over, and some RNA can even be returned to translation. I will discuss our
current understanding of intracellular compartmentalization, rules that govern these
processes and where we are headed.

The seminar will be hosted using Zoom. A Google calendar invite featuring the Zoom link will be sent to Biology staff and students before the seminar date. For all enquiries please contact Biology DMT Hub on biol-dmthub@york.ac.uk.