104Lecture8

104Lecture8 - Lecture 8 4/26/11 Background reading: MBOC 5...

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Unformatted text preview: Lecture 8 4/26/11 Background reading: MBOC 5 th Edition: Chapter 13: pages 750-764; 791-795; 800-809 MBOC 4 th Edition: Chapter 13: pages 712-724; 746-753; 755-763; Outline: • Endocytic pathway. • Receptor-mediated endocytosis. • Polarized cells. • Mechanism of vesicular transport. • Mechanism of entry of HIV virus into cells. • Monomeric GTPases. • Organelle biogenesis. • Endocytic Pathway Leads inward from the secretory pathway Vesicular transport carries glycoproteins through this system and they can undergo various modifications as they proceed through different compartments. Closely linked with the secretory system are retrieval systems as shown by blue arrows and the endocytic system as shown by the green arrows. • Receptor-mediated endocytosis Process by which an external ligand binds to a receptor on the cell surface and is then internalized to endosomes and then passed on to lysosomes. First described by studies of uptake of cholesterol. All animal cells require cholesterol for their membranes but cannot tolerate excess in blood. Therefore the cholesterol is trans- ported in the blood in a complex. Low density lipoprotein (LDL) is the most abundant complex in man and is made in the liver and intestine. Cells that require cholesterol for membrane synthesis have been found to synthesize a receptor that recog- nizes LDL and takes up LDL and delivers it to the lysosomes where it is degraded. In humans there is 1 receptor gene/haploid genome . Familial hypercholesterolemia – genetic diseases where there are mutations in LDL receptor gene. Natural mutations are common. 1 in 500 people have single defective copy of LDL receptor gene and have higher risk of heart attack. Pioneering work on cholesterol uptake by Brown and Goldstein:...
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This note was uploaded on 11/16/2011 for the course BIS 40175 taught by Professor Amenta during the Spring '11 term at UC Davis.

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104Lecture8 - Lecture 8 4/26/11 Background reading: MBOC 5...

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