The ubiquitin proteasome pathway is responsible for most of the protein degradation in mammalian cells. Rates of degradation by this pathway have generally been assumed to be determined by rates of ubiquitylation. However, recent studies indicate that proteasome function is also tightly regulated and determines whether a ubiquitylated protein is destroyed or deubiquitylated and survives longer....

Cysteine cathepsins are a group of enzymes normally found in the endolysosomes where they are primarily involved in intracellular protein turnover but also have a critical role in MHC II-mediated antigen processing and presentation. However, in a number of pathologies cysteine cathepsins were found to be heavily upregulated and secreted into extracellular milieu, where they were found to degrad...

Levine, Elliot M. (National Institutes of Health, Bethesda, Md.). Protein turnover in Escherichia coli as measured with an equilibration apparatus. J. Bacteriol. 90:1578-1588. 1965.-Intercellular protein turnover (the reutilization by one cell of amino acids derived from the protein of another cell) occurs at a rate of 0.16 to 0.18% per hour in nongrowing cultures of Escherichia coli, as determ...

Protein turnover, defined as the degradation and replacement of proteins, appears to vary between most adult species in the same way as metabolic rate, i.e. as W0.75, although it may be a little lower in man. During development in the rat it also varies as metabolic rate. Thus P Total = 14.7 W0.53kg per day. Most of this turnover occurs in nonmuscle tissues (P = 11.3 W0.50kg per day) with prote...

Mutations in the presenilin genes are the most common cause of familial forms of Alzheimer's disease. Although it is well known for its role in the generation of amyloid peptide, Lee et al. (2010) now report that presenilin 1 deficiency also impacts maturation of the lysosomal proton pump, affecting autophagocytosis and protein turnover.