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Fig. 1 | Molecular Medicine

Fig. 1

From: The Alzheimer’s Disease-Associated Presenilins Are Differentially Phosphorylated Proteins Located Predominantly within the Endoplasmic Reticulum

Fig. 1

Antibody specificity and cellular expression of PS proteins in transfected COS-7 cells

(A) Schematic representation of the putative seven transmembrane domain structure of PS proteins. The epitopes and names of the PS antibodies used are indicated. (B) Immunoprecipitations with antibody TOR519 of cell lysates of COS-7 cells mock-transfected or transfected with the PS-1 or PS-2 cDNA. Note the strong augmentation of polypeptides with a molecular weight of 45, 90, and 180 kD (indicated by arrowheads) in PS-1- or PS-2-transfected cells. Antibody TOR519 immunoprecipitates PS-1 and PS-2 proteins. (C) Immunoprecipitations of PS-1 and PS-2 from cell lysates of PS-1- and PS-2-transfected COS cells with antibodies BOS4627 and BOS4624. Note that antibody BOS4627 specifically immunoprecipitates PS-1 and PS-2 proteins whereas antibody BOS4624 selectively identifies PS-1 proteins. *A nonspecific polypeptide immunoprecipitated by BOS4624. Arrowheads indicate the putative PS monomers and oligomers. (D) C-terminal deletions of PS-1 result in a shift of the high-molecular weight proteins described in Panels B and C. Stop codons were introduced after TM7, TM6, TM5, and TM4. COS-7 cells transfected with the corresponding cDNA constructs were metabolically labeled and immunoprecipitated with antibody TOR519. Note the shift of the 45-kD as well as the high-molecular weight proteins, clearly indicating that these represent PS dimers and higher multimers (multimers are indicated by the bracket). (E) The introduction of stop codons after TM6 and TM7 removes the epitopes of the corresponding antibodies. COS-7 cells were transfected with the wt PS-1 cDNA or with PS-1 cDNA constructs containing stop codons inserted after TM6 and TM7. After metabolic labeling, cell lysates were immunoprecipitated with antibodies BOS4624 or BOS4627. Note the loss of the immunoreactivity of the corresponding antibodies after removal of the epitope, which clearly indicates the specificity of the antibodies used.

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