Bio 15 - Bio 15-11-2008 Formation of a multivesicular body...

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Bio 15-11-2008 Formation of a multivesicular body is essential for the destruction of membrane components. The role of multiubiquitination Formation of multivesicular bodies is initiated by tags on the cargo transported by the endosome . The formation of the internal vesicles is believed to be guided by ESCRT-proteins, which recognize the multi-ubiqutin tags on the ctosolic part of cargo However, as far as we know, they not produce the endosomal membrane invagination per se. Mutations of ESCRT-proteins might lead to cancer , since the receptor downregulation of growth factors are inhibited (EGF is a growth factor). Formation of a multivesicular body is also found for HIV and Ebola virus to bud from the plasmamembrane Some virus particle also use the internal vesicle transport to get out of the cell. This mechanism also used the ESCRT complexes for the formation of the multivesicular body . “Pic” In polarized tissues transcytosis transfers after receptor mediated endocytosis the cargo to the other side of the cell Some endosome are used for transcytosis . The classical example for transcytosis is the transfer of antibodies across the endothelium of a babies gut. The cargo in that mechanism is not transferred to the lysosome from the early endosome, but to the other pole of the cell to be excreted there. 1
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Unloading of the vesicle into the extracellular fluid is mediated by the neutral pH . The cargo receptor for the antibody transport is the Fc-receptor binding to the constant part of the antibody. In polarized tissues early endosomes are specialized An epithelial cell has distinct endosomal compartments . The membrane of epithelial cells are separated by tight junctions in two compartments. The basolateral and the apical side of the cell communicate by different endosomal vesicles . 2
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Exocytosis Exocytosis is constitutive of regulated The secretory pathways can be separated into 1- constitutive and 2- regulated pathways . In some cells proteins and phospholipids are transferred constitutively to the plasma membrane. However, in some cells exocytosis has to be regulated to control the secretion process. Exocytosis is regulated The secretory pathways can be separated into constitutive and regulated pathways . -
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This note was uploaded on 05/30/2010 for the course MEDICEN 2100 taught by Professor Saba during the Spring '10 term at Columbia State Community College.

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Bio 15 - Bio 15-11-2008 Formation of a multivesicular body...

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