Biochemical properties of endogenous presenilin 1 and presenilin 2 in cultured human B-lymphocytes

Lukasz Bojarski 1 , 1 , Andrzej Lewandowicz 2 , 2 , Magdalena Blazejczyk 3 , 3 , Adam Sobczak 4 , 4 , Jacek Kuznicki 5 , 5  and Urszula Wojda 6 , 6
  • 1 Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland
  • 2 Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland
  • 3 Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland
  • 4 Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland
  • 5 Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland and Nencki Institute of Experimental Biology, Laboratory of Calcium-Binding Proteins, Warsaw, Poland
  • 6 Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology, Warsaw, Poland

Abstract

Background: Presenilin 1 (PS1) and presenilin 2 (PS2) are membranous proteins involved in the pathology of Alzheimer's disease. The development of specific therapies targeted at PS1 or PS2 requires the determination of biochemical properties of presenilins. Hence, in this study we analyzed the hydrophobic and ionic properties of endogenous presenilins.

Methods: Lysates of immortalized human B-lymphocytes were used as a source of endogenous presenilins. The presence of 3-[(3-cholamidopropyl)dimethylammonio]-2-hydroxy-1-propanesulfonate (CHAPSO) detergent in lysates favored preservation of PS1 and PS2 native protein complexes. We compared Kyte-Doolittle hydropathicity profiles and hydrophobic interactions of PS1 and PS2 with phenyl-agarose. We also compared the ionic properties of presenilins using anion-exchange chromatography.

Results: The hydropathicity profiles of PS1 and PS2 revealed similarly located hydrophobic regions and more hydrophobic region in the C-terminal fragment of PS2. However, both PS1 and PS2 under physiological conditions showed no interactions with phenyl-agarose. Despite similar predicted isoelectric points, PS1 and PS2 exhibited different ionic behavior during anion-exchange chromatography.

Conclusions: The different than expected hydrophobic and ionic behavior of PS1 and PS2 may be caused by interactions with other proteins present in complexes formed by endogenous presenilins. The observed difference in ionic properties of PS1 and PS2 can be further explained assuming that PS1 and PS2 form complexes with different sets of proteins. The composition of such variegated PS1 and PS2 complexes can be explored using a proteomic approach. The difference in PS1 and PS2 ionic behavior can be used for purification of endogenous PS1 from PS2, which has not yet been achieved by any other means.

Clin Chem Lab Med 2007;45:1273–6.

Purchase article
Get instant unlimited access to the article.
$42.00
Log in
Already have access? Please log in.


or
Log in with your institution

Journal + Issues

Clinical Chemistry and Laboratory Medicine ( CCLM) publishes articles on novel teaching and training methods applicable to laboratory medicine. CCLM welcomes contributions on the progress in fundamental and applied research and cutting-edge clinical laboratory medicine. It is one of the leading journals in the field, with an impact factor of over three. CCLM is the official journal of nine national clinical societies and associated with EFLM.

Search