Physiology 3140A Lecture Notes - Lecture 9: Lipid Raft, Caveolin, Vinculin
2 May 2018
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Physiology 3140 Lecture 9
September 27 2017
Membrane Rafts Signaling platforms
Membrane Rafts
- Lipid Rafts
o Small (10-200 nm)
o Heterogeneous
▪ Have a different mix of proteins, cholesterol, and sphingolipids
o Composed of:
▪ Cholesterol
▪ Sphingolipids
▪ Glycerphospholipids
▪ Specialized proteins (caveolin, flotillin, etc.)
o More ordered and tightly packed than surrounding bilayer
▪ MORE RIGID
- Have specific function;
o Concentrate/ separate proteins within the plane of the bilayer
▪ If all the proteins that interact to propagate signal – if they all like lipid rafts, the
lipid raft is somewhere they can congregate
• Concentrate and propagate a signal at the lipid raft
▪ If some proteins in a signalling pathway love lipid raft and others hate it; the
proteins are kept separated
• Have to move one of them out or one of them in
o Compartmentalize cellular processes
Composition:
- Resident proteins: protein that usually stays in the lipid raft
o Identify the lipid raft by these proteins
o Caveolin
o Flotillin
o GPI-anchored proteins (for e.g., prion protein)
- Tourist’ Signaling proteins: come in, stay for a while, and move out
o DO NOT RESIDE IN THE LIPID RAFT
o Some G-proteins
o Non-receptor tyrosinae kinases
- Cytoskeletal/Adhesion proteins (congregate at lipid rafts)
o Actin
o Vinculin
o Cadherin
find more resources at oneclass.com
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Document Summary
Lipid rafts: small (10-200 nm, heterogeneous, have a different mix of proteins, cholesterol, and sphingolipids, composed of: Specialized proteins (caveolin, flotillin, etc. : more ordered and tightly packed than surrounding bilayer, more rigid. Have specific function: concentrate/ separate proteins within the plane of the bilayer. If all the proteins that interact to propagate signal if they all like lipid rafts, the lipid raft is somewhere they can congregate: concentrate and propagate a signal at the lipid raft. If some proteins in a signalling pathway love lipid raft and others hate it; the proteins are kept separated: have to move one of them out or one of them in, compartmentalize cellular processes. Resident proteins: protein that usually stays in the lipid raft. Identify the lipid raft by these proteins: caveolin, flotillin, gpi-anchored proteins (for e. g. , prion protein) Tourist" signaling proteins: come in, stay for a while, and move out: do not reside in the lipid raft, some g-proteins, non-receptor tyrosinae kinases.
