SL+D103+lecture+14+Signaling+VI

SL+D103+lecture+14+Signaling+VI - D103: Cell Biology Dr....

Info iconThis preview shows pages 1–10. Sign up to view the full content.

View Full Document Right Arrow Icon
D103: Cell Biology Dr. Shin Lin
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lecture 14 Signaling VI
Background image of page 2
i-Clicker: cells have to regulate the synthesis and regulation of tens of thousands of different molecules A. Cells have tens of thousands of different regulatory pathways. B. Cells have much fewer than this number of pathways, but use thousands of different and/or similar mechanisms for fine tuning specificity and efficiency. D103 Fall 2011 - Lecture 14 - Signaling VI 3
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 4 D103 Fall 2011 - Lecture 14 - Signaling VI Additional Conserved Principles Cells can adjust their sensitivity to signals. Feedback systems mediate efficient signaling. Efficient control of signaling requires molecules with short half-lives. Scaffolding proteins mediate efficient and specific signaling, and facilitate localized control of feedback. Lipid rafts and phospholipids enable subcellular localization of specific protein machinery. Recommended Reading: MBOC 5e, pages 879 - 940 Additional key concepts and principles used in signaling
Background image of page 4
Page 5 SIMPLIFIED SUMMARY (as previously discussed) of extracellular ligand signaling pathways general component specific example
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 6 general component specific example MORE DETAILED SUMMARY (as previously discussed) of extracellular ligand signaling pathways
Background image of page 6
Page 7 D103 Fall 2011 - Lecture 14 - Signaling VI Some common principles used in signaling Regulation of specificity of protein interactions can be accomplished by subtle conformational change in protein structure. Regulation of specificity of a protein - ligand interaction by covalent modification (e.g. addition or removal of phosphorylation, ubiquitination, sumoylation, proteolysis). Control of subcellular location of protein; e.g. by masking / unmasking of amino acid motifs. Control of steady-state level of protein; e.g. by poly-ubiquitination and degradation . Control of specificity of subcellular signaling; e.g. by scaffold proteins. Control of signaling protein activity by proteolysis (i.e. cleavage, not degradation). Control of signaling response by positive and negative feedback . Amplification of signals and intracellular transduction of signal via small molecules (second messengers). Use of GTPases as timers to control signaling. Use of wide range of functional " domains " (i.e. a region of conserved amino acid sequences) within different proteins. Enabling sophistication and functional redundancy in pathways , by duplication and divergence of genes whose products are involved in signaling.
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Page 8 FEEDBACK LOOPS: POSITIVE FEEDBACK for regulating activity in intracellular signaling networks POSITIVE FEEDBACK mediates a rapid large scale increase in activity of an enzyme in presence of similar steady-state level of ligand. NEGATIVE FEEDBACK achieves opposite effect (see SLIDE on p. 10)
Background image of page 8
Page 9 AMPLIFICATION Intracellular mediators and enzymatic cascades amplify extracellular signals Molecules must have
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Image of page 10
This is the end of the preview. Sign up to access the rest of the document.

Page1 / 25

SL+D103+lecture+14+Signaling+VI - D103: Cell Biology Dr....

This preview shows document pages 1 - 10. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online