Centriolar satellites are small spherical granules (70-100 nm) that can be found clustered around the centrosome in human cells. They consist of protein complexes of variable and dynamic composition, containing many proteins that also localize to the centrosome. Centriolar satellites are anchored to and move along microtubules with the help of motor proteins. Thus, they function as vehicles for protein transport towards, and likely also away from, the centrosome. Moreover, centriolar satellites seem to act as a hub for dynamic regulation of centrosome function and maintenance, as well as of ciliogenesis and neurogenesis, in response to a variety of signals.
Centriolar satellites are found around centrosomes in interphase cells, but they undergo dissolution upon entry into mitosis. In the subcellular section, staining of one or two small dots at the origin of microtubules is annotated as centrosome, whereas a more diffuse, sometimes punctate, staining of this area is annotated as centriolar satellites.
Read more about the proteome of centriolar satellites as a substructure of the centrosome.