Figure 9.17 shows three posttranslational steps required to produce the sugar-regulating hormone insulin from the starting polypeptide product preproinsulin.

Recombinant human insulin (made by inserting human DNA encoding insulin into E. coli) is one of the most widely used recombinant pharmaceutical products in the world. What segments of the human insulin gene are used to create recombinant bacteria that produce human insulin?