Recombinant proteins made in Pichia pastoris

Pichia pastoris is a methylotrophic yeast widely used in the production of recombinant proteins. This eukaryotic expression system has a series of characteristics that make it suitable for this purpose, such as: having a high growth rate, even on simple and economical substrates; it can be grown in both a flask and a fermenter, which makes it useful for both small and large scales; has two genes that encode alcohol oxidases, AOX1 and AOX2, enzymes that have a strongly inducible promoter, with AOX1 being one of the strongest and most regulated promoters available; or the stable integration of the expression plasmids into its genome.

Compared to Escherichia coli, the most used expression system for protein production, the growth process of P. pastoris is slower. However, P. pastoris is capable of generating disulfide bridges, which promotes protein folding. Its glycosylation is quite different from that which takes place in higher eukaryotic systems, so blockers should be used in the detection of IgG and IgM. It is a very suitable expression system for the production of recombinant allergens, where the detection of IgE is not altered by the glycosylation of the system. However, for other proteins of human origin or certain viruses, more sophisticated expression systems will be required.