What are the key steps in producing recombinant human insulin in bacteria?

What are the key steps in producing recombinant human insulin in bacteria?

• A. The human insulin gene is cloned into an expression vector in E. coli; the proinsulin or insulin is expressed, processed to mature form, and purified.
• B. The insulin gene is inserted into yeast and secreted directly as mature insulin without processing.
• C. Insulin is produced by viral expression in mammalian cells.
• D. Insulin is produced by culturing plant cells that glycosylate insulin.

Answer: (A)

Producing recombinant insulin in bacteria relies on expressing the human insulin gene as a precursor that can be converted into the active hormone. The human insulin gene is cloned into an expression vector and introduced into E. coli, where the resulting product is produced as proinsulin or a fusion partner that can be enzymatically cleaved. After expression, proteolytic processing removes the extra peptide to yield mature insulin, and the molecule forms the correct disulfide bonds between the A and B chains. The final step is purification to separate insulin from bacterial proteins and other byproducts. Other approaches—secreting mature insulin directly, using yeast with no processing, viral expression, or plant cells that glycosylate insulin—do not provide the properly processed, non-glycosylated insulin that bacteria typically produce, so they aren’t the standard route for this purpose.

Producing recombinant insulin in bacteria relies on expressing the human insulin gene as a precursor that can be converted into the active hormone. The human insulin gene is cloned into an expression vector and introduced into E. coli, where the resulting product is produced as proinsulin or a fusion partner that can be enzymatically cleaved. After expression, proteolytic processing removes the extra peptide to yield mature insulin, and the molecule forms the correct disulfide bonds between the A and B chains. The final step is purification to separate insulin from bacterial proteins and other byproducts. Other approaches—secreting mature insulin directly, using yeast with no processing, viral expression, or plant cells that glycosylate insulin—do not provide the properly processed, non-glycosylated insulin that bacteria typically produce, so they aren’t the standard route for this purpose.