Figure 1: A candidate screen isolates neurexin1β as an Aβ42 oligomer-interacting protein.
(a) Immunoblotting with an anti-β-Amyloid 1–16 antibody (6E10) confirms the formation of soluble oligomers of untagged amyloid-β (1–42) peptide (Aβ) and of biotin-tagged Aβ42 peptides (biotin-Aβ). The preparations include both low and high molecular weight (HMW) oligomers. The preparation without an oligomerization incubation step (Fresh) does not include HMW oligomers. Full gel blots for the cropped blots (a) are shown in the Supplementary Fig. 4. (b) The biotin-Aβ42 oligomers bind to COS-7 cells expressing the N-terminal extracellular HA-tagged known Aβ42 oligomer receptors, paired immunoglobulin-like receptor B (HA-PirB) and prion protein (HA-PrPc), but not those expressing HA-CD4 as a negative control. Surface HA was immunostained to verify expression of these constructs on the COS-7 cell surface. (c) Representative images showing cell surface binding assays testing for interaction between biotin-Aβ42 oligomers (250 nM, monomer equivalent) and known synaptic organizers. Biotin-Aβ42 oligomers were added to COS-7 cells expressing the indicated construct. Note that biotin-Aβ42 oligomers bind to COS-7 cells expressing HA-neurexin (NRX)1βS4(−), but not to those expressing any of the other organizers including HA-neuroligin1 (HA-NLG1). For the N-terminal extracellular HA-tagged constructs, surface HA was immunostained to verify expression of the construct on the COS-7 cell surface. Scale bars represent 30 μm (b,c).
