Most of the Thermo Scientific Pierce recombinant proteins have been expressed in either an E. coli or Pichia pastoris (yeast) system. All recombinants are low-endotoxin and have been validated via bioassay and SDS-PAGE. Most are also provided in a carrier-free format, ideal for cell culture or production of standards for ELISA or Western blotting. Thermo Scientific Pierce offers a growing number of yeast-derived proteins that offer the added advantage of being glycosylated in a manner similar to mammalian systems.