The Endocytic Pathway Uptake of macromolecules and particles is done by ENDOCYTOSIS. Pinocytosis effectively internalizes portions of the cell membrane, any proteins or receptors on the membrane, and any ligands attached to those receptors. Fate of these receptors and their ligands varies after endocytosis. When soluble Ig binds to antigen, both receptor and ligand are directed to the lysosmes. The other possible route is that vesicles may be transported to another region of the membrane where the ligand is released. One form of pinocytosis involves the use of coated pits [receptor-mediated endocytosis] . Ligand binds to receptor. Complex travels laterally through the membrane to a coated pit region. Complexes are retained and concentrated in these pits. Clathrin is a protein whose subunits form the surface of the pit. Pit then invaginates and eventually forms a vesicle known as a clathrin coated vesicle. The clathrin coated vesicle first fused with vesicles known as early endosomes . Fusion
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This document was uploaded on 11/03/2011 for the course BIOLOGY MCB2010 at Broward College.