Biology 2382B Lecture Notes - Lecture 4: Secretion, Microsome, Signal Peptide
16 Aug 2017
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Document Summary
Typical mammalian cell: 10,000 proteins, must be localized correctly. Newly made peptides must be directed to the correct destination. Targeting: direct proteins to the right destinations (organelles) Involves a signal sequence which tells cell where to take protein. Sorting: direct proteins to the secretory pathway (er, golgi, lysosomes), proteins are then transported to different part of the cell or outside of the cell within vesicles. General principles of protein synthesis, targeting and sorting. Many proteins are synthesized by cytosolic ribosomes: proteins with no signal sequence remain in the cytosol, proteins with a specific signal sequence are targeted to intracellular organelles such as (er), mitochondria, chloroplasts, peroxisomes, and nucleus. Other proteins are synthesized by ribosomes attached to er (rough er): those which reside in er and are sorted to plasma membrane, golgi complex, and lysosomes. Accordingly, two major protein-sorting pathways are known: nonsecretory and secretory: focus primarily on secretory pathway.
