Chapter 17, Problem 5TYR

Summary Introduction

Introduction:

Peptide hormones are synthesized like other protein molecules. They are 3 to ≥ 200 amino acid long chains. Insulin is the large peptide hormone (protein) secreted by the pancreatic islets. The insulin gene is transcribed into the mRNA molecule that codes for insulin protein. Ribosomes bind and read the mRNA molecule and synthesize peptide with the help of tRNA. The rough endoplasmic reticulum and Golgi complex modify the amino acid peptide to mature hormone (protein). The middle portion of the proinsulin (single amino acid chain) is known as the connecting peptide. The connecting peptide (31 amino acids long) is removed from the proinsulin, and the two polypeptide (30 and 21 amino acids long) chains are linked by disulfide bridges to produce the mature insulin molecule.