Localization of Alzheimer-associated presenilin 1 in transfected COS-7 cells.

Presenilin 1 (PS 1) is the recently identified gene, located on chromosome 14, of which missense mutations can cause early-onset familial Alzheimer's disease. To understand the normal biological function of presenilin 1, we examined the sub-cellular localization by using a monoclonal anti-presenilin 1 antibody. Immuno-electronmicroscopic and biochemical analysis indicated that presenilin 1 is localized on cellular membrane (plasma, endoplasmic reticulum, and perinuclear) in COS-7 cells overexpressing presenilin 1. Interestingly, the PS 1 immunoreactivity in the plasma membrane was concentrated in the regions with cell-cell contact. This observation suggests a possible role of PS 1 on the cell membrane as a cell adhesion molecule.