How is recombinant human insulin produced?

Recombinant human insulin is produced using genetically engineered microorganisms. The process involves: 1) Cloning human insulin genes (A and B chains) into expression vectors. 2) Transforming E. coli or yeast (Saccharomyces cerevisiae) with expression constructs. 3) Growing cultures in fermenters under controlled conditions. 4) Expressing insulin as inclusion bodies (E. coli) or secreted protein (yeast). 5) Cell harvest and lysis if needed. 6) Purification through chromatography (ion exchange, reverse phase, size exclusion). 7) Refolding and joining A and B chains with correct disulfide bonds. 8) Formulation with zinc and preservatives. Insulin analogs (lispro, glargine) are created by modifying the amino acid sequence for different pharmacokinetic profiles.