Measuring the Folding Dynamics of Recombinant Proteins Secreted from Mammalian Cells

The biotechnologist faced with the challenge of producing significant quantities of recombinant protein will endeavor to identify a host cell for protein production that will synthesize authentic, biologically active proteins at relatively high yields. Due to the complex folding pathway and posttranslational modifications required for some proteins to elicit full biological activity, the choice of host cell is limited to mammalian cells (for review, see ref. 1 ). The restrictions do not end here, as some cell lines have a greater capacity to carry out specific modifications than others, thus requiring an evaluation of host cells to fold, modify, and secrete the model protein (1 –3 ). This chapter will summarize the main steps in carrying out the evaluation process at a practical level. The protocols are applicable to most proteins but some optimization of conditions will be necessary depending on the protein being studied.