The reference provided focuses on the translation of insulin mRNA into the preproinsulin protein, and its subsequent processing. The question asks about transcription, which is a different process. Therefore, while I can describe the translation process based on the reference, I cannot answer the question of transcription based on the reference alone.
The information about insulin translation is:
The insulin mRNA is translated as a single chain precursor called preproinsulin. Thereafter the removal of its signal peptide during insertion into the endoplasmic reticulum generates proinsulin. Proinsulin consists of three domains: an amino-terminal B chain.
Therefore, translation yields preproinsulin which is then modified to proinsulin and eventually to insulin.
