Lecture 7

Lecture 7 - Lecture #7 Tuesday 4/22/08 -1- Announcements: -...

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Lecture #7 – Tuesday 4/22/08 - 1 - Announcements: - The professor received an email from the Office of Academic Integrity. There is a website that may or may not have old midterms from this class. These were not put up by Professor Johnson and you use them at your own risk. He puts his relevant old tests on Webct anyways. ALWAYS KEEP IN MIND: the professor can change any question/answer from old tests and use them on new tests. So just regurgitating the answers from an old (but similar) test question may not cut it. Back to Chapter 6 and the Ras pathway: We know that Ras: - A critical oncogene - Sits in cell membrane - Interacts with receptor tyrosine kinases (RTK) - Is a GTPase o Active with GTP bound, Inactive with GDP o If a mutation leaves Ras without GTPase activity, it stays on (can’t hydrolyze the GTP) o Keeps GTP in the active site, cannot convert to GDP. Lecture slide images are taken from the book: “Biology of Cancer” by Robert A. Weinberg (your textbook) Figure 6-2: (Talked about this experiment before) - This experiment was first illustrated in the early 80s: Placed serum on quiescent or serum starved 3T3 cells and looked for activated genes. - Following 30 min. time points an hour or two hours, groups of genes began being transcribed - Used to look at genes individually, but this figure illustrates the benefit modern techniques. Because no array or chip methods. We’re able to look at the entire transcribed genome of cells at once. - Shows the immediate activation of gene expression from signal transduction from growth factors in serum. Table 6.1: - c-fos and c-jun are amongst of the transcription factor (TF) gene families that are activated early - Lots of these immediate early genes are nuclear transcription factors. Involved in induction of cell growth pathways. Figure 6.3: Illustrates how the process of Immediate Early Genes Work. Figure 6.4: Cytoskeletal changes that occur upon addition of serum - Stain for actin - Actin is diffuse in quiescent cells
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Lecture #7 – Tuesday 4/22/08 - 2 - - Actin cabling is seen in serum activated cells (so when you add serum) o Cabling is the assembly of proteins in the cytoskeleton that’ll later facilitate/coordinate cell movement and eventual division. o Related to integrin signal transduction andbinding of these actin filaments and assembly of them around cores of focal adhesions (other extracellular matrix proteins (ECM) are also involved) Figure 5.32: How signal transduction pathways fit together to give rise to Ras activation and thus response to mitogens Figure 5.30: Ras - Rapid cycling is characteristic of Ras protein. - Because you want a quick response. Don’t want growth factor (GF) stimulated pathways on for longer than necessary if on for long time - oncogenic signal Figure 6.12a: Tyrosine Kinase - Auto-phosphorylation or cross-phosphorylation between kinases leads to phosphorylation of Tyrosine residues that can be recognized by proteins like Grb2 with SH2 domains (has specific affinity for phosphotyrosines, particularly in
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This note was uploaded on 07/21/2008 for the course BIMM 134 taught by Professor Johnson during the Spring '08 term at UCSD.

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Lecture 7 - Lecture #7 Tuesday 4/22/08 -1- Announcements: -...

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