For cloning of the PrESTs, a pool of RNA consisting of material from a number of human tissues is used in an RT-PCR approach. The amplified gene fragments are cloned and sequence verified. An E. coli recombinant protein expression system is used for expressing the clones and the products are purified using nickel-containing matrices (IMAC).
The expressed PrEST Antigens are validated using ESI mass spectrometry. Purity is analyzed using SDS page and the PrEST Antigen amount is being quantified using the Nanodrop system.