Diabetes-Insulin proinsulin (synthesis, storage, secretion) B cel peptidases Produced within the pancreas by free C peptide Bcells islets of Langerhans insulin mrna is translated as a single chain precursor called preproinsulin removal of signal peptide during insertion into the endoplasmic reticulum generates proinsulin Within the endoplasmic reticulum, proinsulin is exposed Insulin dimer nsulin hexamer to several specific endopeptidases which excise the C peptide, thereby generating the mature form of insulin Stored as阝 granulesDiabetes – Insulin (synthesis, storage, secretion) Zn ◼ Produced within the pancreas by β cells → islets of Langerhans ◼ insulin mRNA is translated as a single chain precursor called preproinsulin ◼ removal of signal peptide during insertion into the endoplasmic reticulum generates proinsulin ◼ Within the endoplasmic reticulum, proinsulin is exposed to several specific endopeptidases which excise the C peptide, thereby generating the mature form of insulin ◼ Stored as β granules