Biology 2382B Lecture Notes - Lecture 6: Dynamin, Cytoskeleton, Low-Density Lipoprotein
24 Aug 2013
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Document Summary
Lysosomal storage diseases are caused by the absence of one or more lysosomal enzymes resulting in the accumulation of undegraded material in lysosomes. One of the most severe types of lysosomal storage disease is inclusion-cell (i-cell) disease. It is caused by the absence of n-acetylglucosamine (glcnac) phosphotransferase, which is required for phosphorylating enzymes bound for the lysosome (that carry the m6p signal). Thus, lysosomal enzymes are secreted rather than being sorted to the lysosomes, resulting in undigested glycolipids (normally degraded by lysosomal enzymes) accumulating in the lysosomes. Lysosomal storage diseases typically have a fatal outcome early on in childhood. Cells internalize extracellular materials through three different types of endocytosis. Phagocytosis is a process by which relatively large particles (e. g. bacterial cells) are internalized by certain eukaryotic cells that involves extensive remodeling of the actin cytoskeleton. Pinocytosis is where small droplets of extracellular fluid and any material dissolved in it are non-specifically taken up.
