Updated project metadata. To determine the dynamics of ribosomal proteins in brain tissues, we isolated monoribosomes and ribosomes engaged in polysomal fractions from three different brain tissues, cerebellum, hippocampus and cortex, and compared them to the liver of CD-1 IGS mouse. We provide a comprehensive unique study of the ribosomal composition among these different tissues along different life stages, from juvenile (three-weeks), young adult (four-months) to mature adults (seven- and twelve-months) of age. The protein composition of the ribosomes was quantified using LC-MS/MS approach.