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Related Experiment Video

Updated: Jul 17, 2026

Imaging the Intracellular Trafficking of APP with Photoactivatable GFP

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Published on: October 17, 2015

The presenilins turned inside out: implications for their structures and functions.

Nazneen N Dewji¹, Dante Valdez, S J Singer

¹Departments of Medicine and Biology, University of California at San Diego, La Jolla, CA 92093, USA. ndewji@ucsd.edu

Proceedings of the National Academy of Sciences of the United States of America

|January 21, 2004

Summary

Presenilin proteins, crucial in Alzheimer's disease, are definitively shown to have a 7-transmembrane (7-TM) structure at the cell surface, challenging the established 8-TM model. This finding necessitates a re-evaluation of presenilin's structure and function.

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Area of Science:

Neuroscience
Cell Biology
Biochemistry

Background:

Presenilin (PS) proteins are integral membrane proteins implicated in Alzheimer's disease pathogenesis.
The widely accepted model describes PS proteins with an eight-transmembrane (8-TM) helix topography within the endoplasmic reticulum membrane.

Purpose of the Study:

To definitively demonstrate the cell surface topography of presenilin-1 (PS-1).
To challenge the prevailing 8-TM model by presenting evidence for an alternative PS topography.

Main Methods:

Immunofluorescence studies utilizing monoclonal antibodies (mAbs).
Analysis of PS-1 in both transfected and untransfected cell lines to detect cell surface expression.

Main Results:

The 7-transmembrane (7-TM) topography of PS-1 at the cell surface was definitively demonstrated.
Evidence was provided for endogenous PS-1 expression at the cell surface with a 7-TM structure.

Conclusions:

The study provides conclusive evidence for a 7-TM model of PS-1 at the cell surface.
These findings compel a significant revision of current understanding regarding the structural and functional properties of presenilin proteins.