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• Last Class:
• 1. transportation at the plasma membrane
• A. carrier protein, B. channel protein
• 2. intracellular compartments
• A. nucleus, B. Endoplasmic Reticulum
The intracellular compartments of the eucaryotic cell in the biosynthetic-secretory and endocytic
pathways
The role of dynamin in pinching off clathrin-coated vesicles from the membrane
Shibire mutant in drosophila
The functional compartmentalization of the Golgi apparatus
Notice of multiple steps involving glycosylation
Two possible models explaining the
organization of the Golgi apparatus and the
transport of proteins from one cisterna to the next
Phagocytosis by a macrophagePhagocytosis: large particle, >250nm
Pinocytosis: fluid, liquid, 100 nmOne macrophage and two red blood cells
Sorting of membrane
proteins in the endocytic pathwayGreen: EGF-EGFRRed: transferrin and its receptor
Summary
•Intracellular vesicular traffic, SNARE, GAB, Clathrin, Dynamin, Adaptin
•ER->Golgi, COPII, COPI
•Golgi->lysosome, acid hydrolases, M6P
•endocytosis, phagocytosis, pinocytosis, clathrin-coated pit, caveolae,
•Exocytosis, constitutive and regulated mechanisms
For Long distance, two typical ways
Endocrine signalingDifferent cells need specific ligands and receptors
NO (nitric oxide) induces the relaxation of SMCThe function of viagra is to inhibit cyclic GMP phosphodiesterase, hence elongate the lifetime of cyclic GMP and relaxation
Cell Surface receptors belong to three classes: 1. ion-channel-linked receptors, 2. G-protein-linked receptors, 3. enzyme-linked receptors
Cell Surface receptors belong to three classes: 1. ion-channel-linked receptors, 2. G-protein-linked receptors, 3. enzyme-linked receptors
Different Kinds of intracellular proteins serving as signaling molecules
1. Relay proteins2. Messenger proteins3. Adaptor proteins4. Amplifier proteins5. Transducer proteins6. Bifurcation proteins7. Integrator proteins8. Latent gene regulatory proteins
Intracellular signaling complexes enhance the speed, efficiency, and specificity
2 types: Preassembled vs. Assembled after stimulation
Intracellular signaling complexes enhance the speed, efficiency, and specificity
2 types: Preassembled vs. Assembled after stimulation
Cells can be sensitive to subtle difference in environment
1. Multiple ligands are needed for one signaling molecule
Cells can be sensitive to subtle difference in environment
2. Multiple ligated molecules are needed to be assembled to be functional
Cells can be sensitive to subtle difference in environment
3. Positive feedback can enhance the response drastically
Summary
• Typical signaling transduction pathway: 1. ligand-receptor, 2. gap junctions
• Different inputs, receptors, intracellular signaling network determine the ultimate response
• The importance of lifetime of molecules• Different steps of responses• The types of receptors: ion-channel-linked, G
protein coupled, enzyme-linked receptors• Intracellular signaling molecules, signaling switches,
signaling integration, signaling complex assembly, protein-protein binding modulus, signaling amplification, signaling desensitization