Membrane definition

Golgi apparatus

The Golgi apparatus is a series of flattened, cisternal membranes andsimilar vesicles usually arranged in close apposition to each other toform stacks. In mammalian cells, the Golgi apparatus is juxtanuclear,often pericentriolar. The stacks are connected laterally by tubules tocreate a perinuclear ribbon structure, the 'Golgi ribbon'. In plantsand lower animal cells, the Golgi exists as many copies of discretestacks dispersed throughout the cytoplasm. The Golgi is a polarizedstructure with, in most higher eukaryotic cells, a cis-face associatedwith a tubular reticular network of membranes facing the endoplasmicreticulum, the cis-Golgi network (CGN), a medial area of disk-shapedflattened cisternae, and a trans-face associated with another tubularreticular membrane network, the trans-Golgi network (TGN) directedtoward the plasma membrane and compartments of the endocytic pathwayThe Golgi apparatus receives the entire output of de novo synthesizedpolypeptides from the ER, and functions to posttranslationally processand sort them within vesicles destined to their proper finaldestination (e.g. plasma membrane, endosomes, lysosomes)