As expected, cell-surface S100A7 binding activity was detected in cultured CHO-APPswe cells (Fig. 8B) as well as and in the granular layer of mouse hippocampal formation with a preferential distribution with the neuropil (Fig. 8C); AP treated samples resulted in background staining, as expected (Fig. 8B.C).
We verified the purity of sorted populations by re-sorting an aliquot of the isolated cells for the same surface markers used for their isolation and found that >95% of the cells had the expected cell-surface phenotype.
Of 52 membrane proteins examined, 27 revealed the expected cell-specific cell-surface expression pattern and 25 antibodies failed due to absence of signal in all assays tested or were detected as multiple bands by western blot (see Supplemental Experimental Procedures for antibody details).
Furthermore, both human CD81 and OCLN had a dominant hepatic expression with expected hepatic cell surface localization (Supplementary information, Figure S1D and S1E).
Co-culture of macrophages and REM134 cells was also able to inhibit the expression of M2 macrophage marker CD301 in response to LPS-induced activation, contrary to what would be expected; this cell surface marker was anticipated to be increased with cancer cell-stimulation of the macrophages (Fig. 1b).
Furthermore, since certain ligands such as BMP2, BMP4 or GDF5 can interact independently with type I as well as type II receptors [ 12, 13] an inherent complexity of individual ligand-receptor interactions can be expected on cell surfaces.
As expected, we found cell surface expression of both murine and human CEACAM1 on splenic B-cells, but not on splenic T-cells.
As expected for a cell surface molecule, the staining signal was associated mainly with chondrocyte membranes and pericellular areas.
Interestingly, this was not accompanied by an increase in PS1-CTF/Pen-2, as might be expected if more cell surface N33A Pen-2 is in mature γ-secretase.
In cells infected with FILORAB1, only RABV G was detected on the cell surface as expected (Figs 2a, b, panel FILORAB1) whereas for the LASSARAB-ΔG and rVSV-GPC-infected cells, LASV GPC but not RABV G was detected on the cell surface (Fig. 2b panel LASSARAB-ΔG/rVSV-GPC).
