Exam 2 will be held Friday October 23rd in the Tes ng Center Arjona 110 You must sign up for an available Exam Slot on HuskyCT Exam Registra on Link There is no regular class on exam day If you have another class con ict with all the available slots you must provide a screenshot of your UConn schedule and contact me ASAP HuskyCT Materials will be unavailable online that Friday Be sure to download any materials you want if you plan on last minute studying There will be 2 Review sessions before the Exam 1 Wednesday 10 21 6 8pm TLS 154 2 Thursday 10 22 6 8pm TLS 154 Bring your Problem Sets The early exam for people with legi mate reasons that have been cleared with me will be on Thursday 10 22 2 00 3 30pm BPB 201 If you need to take the early exam for a legiImate reason and have NOT contacted me yet please do so ASAP david daggeO uconn edu Students who have CSD Exam me place accommoda ons will be taking the exam at the CSD o ce Please get any Exam AdministraIon Forms to me ASAP Vesicle Tra cking From the TGN to the cell surface and back Movement of vesicles to and from the plasma membrane TGN sor ng pathways The Trans Golgi Network Some modi caIons are made to carbohydrates here This is the sorIng compartment of the Golgi Controls the ow of vesicles outward toward the plasma membrane If no added signal proteins move on to secretory vesicles which fuse with the plasma membrane cons tu ve secre on exocytosis This dumps lumen contents outside the cell Puts membrane proteins in the plasma membrane If a signal is present the protein is diverted Lysosomes Regulated secre on exocytosis Some unknown signal must retain certain proteins in the Golgi A roadmap of vesicular transport secretory endocy c retrieval Lysosomes are cytoplasmic vesicles that take part in degradaIon of macromolecules Internal environment is acidic due to a membrane pump that transports H in using ATP as an energy source Contents are hydrolyIc enzymes degrade macromolecules that work in an acid environment acid hydrolases Protease degrades protein DNase degrades DNA RNase degrades RNA Glycosidase degrades polysaccharides Lysosomal component containing vesicles from the golgi fuse with incoming endocyIc vesicles to create late endosomes that mature into lysosomes DegradaIon takes place in both The degraded material can be transported to the cytoplasm and used for synthesis or dumped out of the cell Lysosomes How are Lysosomal Proteins targeted to Lysosomes The primary recogniIon signal is not a simple amino acid sequence but seems to be a general aspect of protein terIary shape signal patch Once recognized the signal leads to the addiIon of a mannose 6 phosphate onto the oligosaccharide chain in the cis Golgi Man 6 P is recognized by a Man 6 P receptor in the Trans Golgi Network that sorts proteins away from secretory path and to lysosome path In the lysosome the pH drops causing the receptor to release the enzyme In the lysosome the phosphate is removed so the targeIng signal is no longer there The receptor recycles back to the TGN Man 6 P Addi on to Lysosomal Enzymes in the Golgi 1 Signal patch recognized by phosphotransferase 2 Mannose 6 phosphate added to enzyme Tra cking enzymes to and from lysosomes M 6 P receptor interacts with clathrin coat adapter proteins Di erent coated vesicles serve speci c steps COP II subunits Clathrin The rst coat protein discovered Forms triskelions three legged structure Can self assemble in test tube in vitro into polyhedral cage This assembly presumably drives membrane budding Arf regulated Various Adapter Proteins AP1 2 etc control cargo speci city Human Lysosomal Storage Diseases Rare human geneIc diseases lead to formaIon of inclusion bodies in cells vesicles full of stu that is normally broken down in lysosome In some diseases Hurlers disease a single type of enzyme is missing and accumulates certain types of macromolecules In some diseases none of the lysosomal enzymes are packaged correctly I cell diseases Inclusion body diseases Man 6 P receptor muta ons Man 6 P transferase muta ons Human Lysosomal Storage Diseases Rare human geneIc diseases lead to formaIon of inclusion bodies in cells vesicles full of stu that is normally broken down in lysosome In some diseases Hurlers disease a single type of enzyme is missing and accumulates certain types of macromolecules In some diseases none of the lysosomal enzymes are packaged correctly I cell diseases Inclusion body diseases Man 6 P receptor muta ons Man 6 P transferase muta ons Where did the enzymes go Human Lysosomal Storage Diseases Rare human geneIc diseases lead to formaIon of inclusion bodies in cells vesicles full of stu that is normally broken down in lysosome In some diseases Hurlers disease a single type of enzyme is missing and accumulates certain types of macromolecules In some diseases none of the lysosomal enzymes are packaged correctly I cell diseases Inclusion body diseases Man 6 P receptor muta ons Man 6 P transferase muta ons Where did the enzymes go How would the enzymes di er with these muta ons How could you detect this Lysosomal targe ng summary MulIple signal and receptor recogniIon events Hydrophobic signal sequence SRP receptor targets protein to ER Glycosyla on site Asn X Ser Thr ER export sequences for cargo receptors that sort lysosome proteins into COPII vesicles bound for CGN Signal patch phosphotransferase leads to Man 6 P addiIon in cisgolgi Man 6 P Man 6 P receptors in the TGN or plasma membrane sort proteins into clathrin coated vesicles bound for late endosomes lysosomes In this case there are mulIple pathways for the cell to use these signals TargeIng of new enzymes from the Golgi TargeIng of mis secreted enzymes through endocytosis recycling see previous tra cking gure some Man 6 P receptors must get secreted too Both the protein and carbohydrate play a role in targeIng Defects in the targeIng system lead to the enzymes being targeted to an incorrect locaIon Endocytosis Movement of membranes vesicles into the cell Pinocytosis uptake of soluble uid phase material from outside the cell Phagocytosis engulfment of solid material from outside by direct aOachment Material from both can end up in lysosomes Phagocytosis Contact of parIcle bacteria etc with surface receptors sImulates the uptake process The surface zippers around the parIcle to engulf it An outward protrusion of membrane driven by acIn laments rather than an inward budding RecogniIon is through surface molecules on the parIcle or