Structural studies of the transmembrane C-terminal domain of the amyloid precursor protein (APP): Does APP function as a cholesterol sensor?

Andrew J. Beel, Charles K. Mobley, Jun Kim Hak, Fang Tian, Arina Hadziselimovic, Bing Jap, James H. Prestegard, Charles R. Sanders

Research output: Contribution to journalArticlepeer-review

144 Scopus citations


The amyloid precursor protein (APP) is subject to alternative pathways of proteolytic processing, leading either to production of the amyloid-β (Aβ) peptides or to non-amyloidogenic fragments. Here, we report the first structural study of C99, the 99-residue transmembrane C-terminal domain of APP liberated by β-secretase cleavage. We also show that cholesterol, an agent that promotes the amyloidogenic pathway, specifically binds to this protein. C99 was purified into model membranes where it was observed to homodimerize. NMR data show that the transmembrane domain of C99 is an α-helix that is flanked on both sides by mostly disordered extramembrane domains, with two exceptions. First, there is a short extracellular surface-associated helix located just after the site of α-secretase cleavage that helps to organize the connecting loop to the transmembrane domain, which is known to be essential for Aβ production. Second, there is a surface-associated helix located at the cytosolic C-terminus, adjacent to the YENPTY motif that plays critical roles in APP trafficking and protein-protein interactions. Cholesterol was seen to participate in saturable interactions with C99 that are centered at the critical loop connecting the extracellular helix to the transmembrane domain. Binding of cholesterol to C99 and, most likely, to APP may be critical for the trafficking of these proteins to cholesterol-rich membrane domains, which leads to cleavage by β- and γ-secretase and resulting amyloid-β production. It is proposed that APP may serve as a cellular cholesterol sensor that is linked to mechanisms for suppressing cellular cholesterol uptake.

Original languageEnglish (US)
Pages (from-to)9428-9446
Number of pages19
Issue number36
StatePublished - Sep 9 2008

All Science Journal Classification (ASJC) codes

  • Biochemistry


Dive into the research topics of 'Structural studies of the transmembrane C-terminal domain of the amyloid precursor protein (APP): Does APP function as a cholesterol sensor?'. Together they form a unique fingerprint.

Cite this