Might act as an inhibitor of spontaneous calcium carbonate precipitation. May be associated with neuronal sprouting in brain, and with brain and pancreas regeneration. In pancreatic acinar cells and, in lower levels, in brain. Enhanced expression of PSP-related transcripts and intraneuronal accumulation of PSP-like proteins is found in brain from Alzheimer disease and Down syndrome patients. High expression levels in fetal and infant brains; much lower in adult brains. The composition of the O-linked carbohydrate on Thr-27 is complex and varied. In the crystallographic structure, the attached sugar appears to be N-acetylglucosamine, typical of an intracellular protein, rather than N-acetylgalactosamine. Lithostathine A