Cellular proteostasis refers to the balance and maintenance of proteins within a cell. It involves the synthesis, folding, and degradation of proteins to ensure they function correctly. Proper proteostasis is crucial for cellular health, as misfolded or damaged proteins can lead to diseases such as Alzheimer's disease and Parkinson's disease. Cells utilize various mechanisms to maintain proteostasis, including molecular chaperones that assist in protein folding and proteasomes that degrade unwanted proteins. Additionally, the endoplasmic reticulum plays a key role in monitoring protein quality. Together, these systems help preserve cellular function and prevent stress-related damage.