Biology: How the Golgi Sorts, Edits, and Ships Proteins

Every eukaryotic cell runs an internal delivery network, and few examples show it as clearly as the pancreatic acinar cell, which manufactures digestive enzymes for export. New proteins begin life at ribosomes on the rough endoplasmic reticulum (RER), the first stop in a journey that continues through the Golgi apparatus and ends in secretory vesicles near the plasma membrane. The Golgi is the system's sorting and finishing centre: stacked, flattened membranous sacs, or cisternae, arranged with a distinct cis face receiving cargo and a trans face shipping it onward. Because each cisterna carries different modifying enzymes, a protein passing through is edited in ordered, sequential steps before packaging. Tracking this route with radioactive 3H-leucine reveals the timing of each handover, so the interval between compartments, calculated simply as the difference between peak times, reflects how long processing and vesicle budding actually take.