BCOR 103 1st Edition Lecture 13 Outline of Last Lecture I Membrane Secretory Pathway II Protein Translocation Outline of Current Lecture I Sorting of Proteins II Uptake of Materials in the Plasma Membrane Current Lecture The Golgi complex is largely responsible for getting proteins to their final destination The four major parts of protein sorting are Golgi localization ER Golgi exchange lysosomal targeting and secretion The Golgi localizes the proteins that are meant to remain in the Golgi Occasionally proteins within the ER will be needed in the Golgi When this happens the protein is tagged with a KDEL which allows the protein to dock in the Golgi but then ultimately be returned to the ER Some proteins need to be transported to a lysosome This process happens in a series of steps First the lysosomal enzymes are inserted through the membrane of the ER and are glycosylated and sent to the Golgi Next the cis Golgi the proteins are recognized and a sugar group is added This sugar group is called a Mannose 6 Phosphate tag After the protein arrives at the Trans Golgi it will sent and received by the receptor for Mannose 6 Phosphate It is then put into a vesicle and transported through the cytosol to the lysosome The last type of sorting that occurs is secretion Secretion occurs from the Trans Golgi Network TGN in two pathways constitutive and regulated The constitutive pathway carries out the ongoing delivery proteins to the plasma membrane for export The regulated pathway has a series of steps to secrete a protein The specific amino acid sequence on the protein binds to a granin protein that is contained the Cis Golgi Once it reaches the Trans Golgi the hydrogen and calcium within the Trans Golgi causes the protein to become insoluble Specific receptors bind the protein granule and then a vesicle buds off from the Golgi and travels to the plasma membrane Uptake of materials at the plasma membrane is comprised of three processes The first is phagocytosis or cell eating In this process the cell membrane slowly engulfs smaller organisms or material The second is pinocytosis or cell drinking This process is the nonspecific uptake of an extracellular fluid into the cell The last process is receptor mediated endocytosis There are four steps involved First the material is bound to an integral These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute membrane receptor Next the receptor and material pinch off and enter the cell This vesicle fuses with endosomes and the acidification leads to the release of the material
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