BSC 300 Lecture Notes - Lecture 17: Unfolded Protein Response, Ern1, Pyrophosphate
Document Summary
Secretory pathway (proteins entering the endomembrane system): ribosomes initiates nascent protein synthesis in the cytosol, er signal sequence directs ribosome docking onto rough endoplasmic reticulum (er) import apparatus. Like other organelles, the er is highly dynamic undergoing continual turnover and reorganization: divided into two subcompartments, rer and ser. Smooth er: extensively developed in a number of cell types; functions include: Synthesis of steroid hormones in endocrine cells: endocrine cells of the gonad and adrenal cortex: detoxification in the liver of various organic compounds: home of the p450 enzymes. Sequestration of calcium ion from cytoplasm of muscle cells: contain a high concentration of calcium-binding proteins. Synthesis of most membrane lipids: most cellular proteins synthesized in 1 of 2 places, ex. cholesterol. In cytoplasm on free ribosomes not bound to membranes: proteins in cytosol, peripheral proteins on membranes, proteins transported into nucleus, proteins incorporated into peroxisomes, mitochondria, and plastids. Bound to surface of rer: begins in cytoplasm.