BIOB10H3 Lecture Notes - Lecture 10: Secretion, Exocytosis, Cell Membrane
Document Summary
Exocytosis: fusion of the vesicles with the plasma membrane: membrane protein can be inserted into the plasma membrane, proteins can be excreted into extracellular space. Two pathways: constitutive secretory pathway, operates continuously, found in all eukaryotic cell, vesicles fuse, stuff gets secreted out, regulated secretory pathway, does not happen continuously, found in cell specialized for secreting stuff rapidly, e. g. neurotransmitters. Secretion: soluble proteins and other substances are stored in secretory vesicles for later release by exocytosis until needed or until a signal is released. Three classes of proteins leaving the tgn: destined for lysosomes (already talked about, immediate delivery to cell surface (exocytosis, constitutive secretory pathway, destined for secretory vesicles (exocytosis, regulatory secretory pathway. Cells specialized for releasing products on demand, and possibly in large quantities use dense-core secretory granules. Vesicles fuse together to form the immature secretory vesicle. Most of the secretory vesicle membranes are only loosely wrapped around the clusters of secretory proteins.
