Enrichment of Plasma Membrane Proteins Using Nanoparticle Pellicles: Comparison between Silica and Higher Density Nanoparticles

Proteomic and other characterization of plasma membrane
proteins
is made difficult by their low abundance, hydrophobicity, frequent
carboxylation, and dynamic population. We and others have proposed
that underrepresentation in LC-MS/MS analysis can be partially compensated
by enriching the plasma membrane and its proteins using cationic nanoparticle
pellicles. The nanoparticles increase the density of plasma membrane
sheets and thus enhance separation by centrifugation from other lysed
cellular components. Herein, we test the hypothesis that the use of
nanoparticles with increased densities can provide enhanced enrichment
of plasma membrane proteins for proteomic analysis. Multiple myeloma
cells were grown and coated in suspension with three different pellicles
of three different densities and both pellicle coated and uncoated
suspensions analyzed by high-throughput LC-MS/MS. Enrichment was evaluated
by the total number and the spectral counts of identified plasma membrane
proteins.