Pathogenic cysteine mutations affect progranulin function and production of mature granulins.

Frontotemporal dementia with ubiquitin-positive inclusions (FTLD-U) can be caused by mutations in the progranulin gene (GRN). Progranulin (PGRN) is a cysteine-rich growth factor, which is proteolytically cleaved by elastase to produce several granulins (GRNs). All FTLD-U mutations in GRN characterized to date result in reduced secreted PGRN protein.

Intracellular protein degradation in mammalian cells: recent developments.

In higher organisms, dietary proteins are broken down into amino acids within the digestive tract but outside the cells, which incorporate the resulting amino acids into their metabolism. However, under certain conditions, an organism loses more nitrogen than is assimilated in the diet. This additional loss was found in the past century to come from intracellular proteins and started an intensive research that produced an enormous expansion of the field and a dispersed literature.