Fig. 2

Enrichment of proteins in cell lysates by urea extraction and in serum/plasma by immunocentrifugation. a, c Measurement of proteins in cell lysates and in serum/plasma using the BCA assay. a The lysate proteins of TykNu cells after digestion by RIPA or 8 M urea were measured using the BCA assay. c Efficiency of the binding of high-abundance proteins (HAPs) to immuno-affinity columns. HAPs in human plasma (HP) or serum (HS) after column separation were measured by BCA and the efficiency of HAPs binding to the column is shown. b, d Confirmation of enriched proteins in urea and RIPA lysates and enriched low-abundance proteins (eLAPs) in serum/plasma by gel separation. Denatured peptides/proteins of either RIPA or urea lysates were separated by SDS-PAGE and were visualized by coomassie staining, eLAPs indicates enriched low-abundance proteins and BSA is bovine serum albumin. The asterisk (*) indicates the relative enrichment of peptides/proteins in cell lysates and in depleted serum/plasma, compared to the original serum/plasma