Cell Biol Lecture-2
This document was uploaded by user and they confirmed that they have the permission to share it. If you are author or own the copyright of this book, please report to us by using this DMCA report form. Report DMCA
Overview
Download & View Cell Biol Lecture-2 as PDF for free.
More details
- Words: 1,401
- Pages: 53
Signal Transduction Section of Cell Biology
Signaling by G Proteins: –– Heterotrimeric G Proteins –– Ras Superfamily Small GTPases (small GTPbinding proteins) Copyright (c) by W. H. Freeman and Company
Signaling through small GTPases ❚ Small GTPases are monomeric guanine nucleotidebinding proteins of 2025 kDa molecular mass ❚ They play major roles in the regulation of growth, morphogenesis, cell motility, axonal guidance, cytokinesis, and trafficking ❚ The first small GTPase to be discovered was Ras ❚ Five families: Ras, Rho, Rab, ARF, and Ran
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Ras ❚ The HaRas and KiRas genes were first discovered as the vHaRas and vKiRas oncogenes of sarcoma viruses around 1980 ❚ The cellular oncogenes were identified in humans in 1982 1983 ❚ Found in mutated oncogenic forms in a large number of human tumors (~30%) ❚ A key regulator of cell growth ❚ The first target of Ras identified was adenylyl cyclase in yeast ❚ The first mammalian signaling pathway involving Ras to be discovered was the Raf/MEK/EERK cascade ❚ Other Ras effectors include PI3K, RalGDS, p120GAP,... Copyright (c) by W. H. Freeman and Company
(aa 3037) (aa 5976)
Copyright (c) by W. H. Freeman and Company
Lipid modification is necessary for binding to membrane and regulators and for activating downstream effectors
Farnesylation at the Cys residue followed by the proteolytic removal of the AAX portion and the carboxylmethylation of the exposed Cys residue. HRas, NRas and KRasA have additional Cys residues that Copyright (c) by W. H. Freeman and Company are further palmitoylated.
Anchoring of integral proteins to the plasma membrane by hydrocarbon chains
Copyright (c) by W. H. Freeman and Company
Ras cycles between active and inactive forms
Copyright (c) by W. H. Freeman and Company
Structures of Ras∙GDPSos complex and Ras∙GTP
Copyright (c) by W. H. Freeman and Company
MAP kinase pathways ❚ Ras proteins mediate their effects on cell proliferation mainly by activation of a kinase signal cascade that culminates in activation of MAP kinase ❚ MAP kinase is a serine/threonine kinase that can translocate into the nucleus and phosphorylate many different proteins, including transcription factors that regulate gene expression
Copyright (c) by W. H. Freeman and Company
An adapter protein and GEF link most activated RTKs to Ras
Copyright (c) by W. H. Freeman and Company
Signals pass from activated Ras to a cascade of protein kinases
(1433, phospholipids Ser/Thr Kinase, Tyr kinase)
Copyright (c) by W. H. Freeman and Company
MAP kinase regulates the activity of many transcription factors
Elk1 Copyright (c) by W. H. Freeman and Company
Various types of receptors transmit signals to MAP kinase
Copyright (c) by W. H. Freeman and Company
Yeast Pheromone Pathway
Copyright (c) by W. H. Freeman and Company
Multiple MAP kinase pathways are found in yeast
Copyright (c) by W. H. Freeman and Company
Yeast MAPK Pathways
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Ras Targets Multiple Effectors
Ras effector mutants Overexpression or Membranetarget Copyright (c) by W. H. Freeman and Company KO cells
Copyright (c) by W. H. Freeman and Company
Rho ❚ The Rho gene was discovered as a homolog of the Ras gene in Aplysia in 1985 ❚ Three major subfamilies: Rho, Rac, and Cdc42, which control the actin cytoskeleton in distinct ways ❚ Another major role is the regulation of gene expression ❚ Activity is controlled by RhoGEF and RhoGAP proteins ❚ Cell movement, axonal guidance, cytokinesis, and morphogenetic processes involving changes in cell shape and polarity
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Activation of RhoGEFs By Extracellular Signals
Copyright (c) by W. H. Freeman and Company
Structure of protooncogene Vav (DH domain)
Copyright (c) by W. H. Freeman and Company
Translocation of RhoGEF
Copyright (c) by W. H. Freeman and Company
Effectors of Rho Proteins
Copyright (c) by W. H. Freeman and Company
Effectors of Rac and Cdc42 Proteins
Copyright (c) by W. H. Freeman and Company
Function of Rho Family Proteins ❚ The function of of the Rho family was first demonstrated in yeast: budding and cell polarity ❚ In mammals, the function of Rac was the first to be clarified: Rac1, in addition to two other cytosolic proteins p47phox and p67phox, were shown to be required for the activation of NADPH oxidase of phagocytic cells ❚ The function of mammalian Rho was elucidated by use of an exoenzyme named C3 (an inhibitor): in cytoskeletal control
Copyright (c) by W. H. Freeman and Company
Stress fiber formation and focal adhesion
Lamellipodial extension and membrane ruffles
Filopodia or microspikes Copyright (c) by W. H. Freeman and Company
Reorganization of the Actin Cytoskeleton ❚ Rho: Actin stress fibers: bundles of actin filaments that traverse the cell and are linked to theextracellular matrix through focal adhesions ❚ Rac: Lamellipodia: thin protrusive actin sheets that dominate the edges of cultured fibroblasts and many migrating cells; membrane ruffles observed at the leading edge of the cell result from lamellipodia that life up off the substratum and fold backward ❚ Cdc42: Filopodia: fingerlike protrusions that contain a tight bundle of long actin filaments in the direction of the protrusion. They are found primarily in motile cells and neuronal groath cones. Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Rab ❚ The first Rab genes discovered were the YPT1 and SEC4 genes in yeast ❚ Number at least 30 ❚ Play key roles in the secretory and endocytic pathways ❚ Located in distinct cellular compartments ❚ Facilitate the formation of vSNARE/tSNARE complexes, which are integral components of vesicle trafficking ❚ It is proposed that Rabs act by recruiting specific docking factors (Exocyst, Rabaptins) from the cytosol to facilitate pairing of the SNAREs ❚ Transport vesicles carry RabGTP. After membrane fusion, GTP hydrolysis converts to RabGDP Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
ARF ❚ The first ARF was discovered as a stimulatory cofactor required for the ADPribosylation of the Gαs by cholera toxin in 1984 ❚ Three classes of ARF ❚ Critical components of several vesicular trafficking pathways ❚ ARFGEF: Sec7 domain ❚ ARFGAP ❚ Relative lack of information about the class II (ARF 4 and 5) and III (ARF6) ARFs ❚ Interacts with PLD, PIP2, coatomers, arfaptin Copyright (c) by W. H. Freeman and Company
ER to Golgi and intraGolgi transport
Formation of a transport vesicle begins when activated ARFGTP associates with the cytoplasmic surface of a donor membrane. How the initiation site is identified remains unknown. Activated ARF interacts with a coat protein, one of seven in the coatomer complex. Recruitment of multiple ARF molecules followed by coatomers causes membrane deformation and budding. Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Ran ❚ Rasrelated nuclear protein ❚ Play a central role in protein and RNA trafficking in and out of the nucleus ❚ Macromolecules travel in and out of the nucleus through nuclear pore complexes (NPCs) and utilize different receptors and carriers. ❚ Almost all the receptors interact with GTPRan and are regulated by the Ran GTPase cycle ❚ Ran functions to trigger the assembly or disassembly of transport complexes ❚ RanGEF in nucleus and RanGAP in cytoplasm Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Signaling through small GTPases ❚ ❚ ❚ ❚ ❚
Ras: Raf/MEK/ERK, cell growth (gene expression) Rho: Actin cytoskeleton and gene expression Rab: Secretory and endocytic pathways (Vesicle trafficking) ARF: Vesicle budding Ran: Nucleocytoplasmic Transport (and microtubule organization)
Copyright (c) by W. H. Freeman and Company
Signaling by G Proteins: –– Heterotrimeric G Proteins –– Ras Superfamily Small GTPases (small GTPbinding proteins) Copyright (c) by W. H. Freeman and Company
Signaling through small GTPases ❚ Small GTPases are monomeric guanine nucleotidebinding proteins of 2025 kDa molecular mass ❚ They play major roles in the regulation of growth, morphogenesis, cell motility, axonal guidance, cytokinesis, and trafficking ❚ The first small GTPase to be discovered was Ras ❚ Five families: Ras, Rho, Rab, ARF, and Ran
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Ras ❚ The HaRas and KiRas genes were first discovered as the vHaRas and vKiRas oncogenes of sarcoma viruses around 1980 ❚ The cellular oncogenes were identified in humans in 1982 1983 ❚ Found in mutated oncogenic forms in a large number of human tumors (~30%) ❚ A key regulator of cell growth ❚ The first target of Ras identified was adenylyl cyclase in yeast ❚ The first mammalian signaling pathway involving Ras to be discovered was the Raf/MEK/EERK cascade ❚ Other Ras effectors include PI3K, RalGDS, p120GAP,... Copyright (c) by W. H. Freeman and Company
(aa 3037) (aa 5976)
Copyright (c) by W. H. Freeman and Company
Lipid modification is necessary for binding to membrane and regulators and for activating downstream effectors
Farnesylation at the Cys residue followed by the proteolytic removal of the AAX portion and the carboxylmethylation of the exposed Cys residue. HRas, NRas and KRasA have additional Cys residues that Copyright (c) by W. H. Freeman and Company are further palmitoylated.
Anchoring of integral proteins to the plasma membrane by hydrocarbon chains
Copyright (c) by W. H. Freeman and Company
Ras cycles between active and inactive forms
Copyright (c) by W. H. Freeman and Company
Structures of Ras∙GDPSos complex and Ras∙GTP
Copyright (c) by W. H. Freeman and Company
MAP kinase pathways ❚ Ras proteins mediate their effects on cell proliferation mainly by activation of a kinase signal cascade that culminates in activation of MAP kinase ❚ MAP kinase is a serine/threonine kinase that can translocate into the nucleus and phosphorylate many different proteins, including transcription factors that regulate gene expression
Copyright (c) by W. H. Freeman and Company
An adapter protein and GEF link most activated RTKs to Ras
Copyright (c) by W. H. Freeman and Company
Signals pass from activated Ras to a cascade of protein kinases
(1433, phospholipids Ser/Thr Kinase, Tyr kinase)
Copyright (c) by W. H. Freeman and Company
MAP kinase regulates the activity of many transcription factors
Elk1 Copyright (c) by W. H. Freeman and Company
Various types of receptors transmit signals to MAP kinase
Copyright (c) by W. H. Freeman and Company
Yeast Pheromone Pathway
Copyright (c) by W. H. Freeman and Company
Multiple MAP kinase pathways are found in yeast
Copyright (c) by W. H. Freeman and Company
Yeast MAPK Pathways
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Ras Targets Multiple Effectors
Ras effector mutants Overexpression or Membranetarget Copyright (c) by W. H. Freeman and Company KO cells
Copyright (c) by W. H. Freeman and Company
Rho ❚ The Rho gene was discovered as a homolog of the Ras gene in Aplysia in 1985 ❚ Three major subfamilies: Rho, Rac, and Cdc42, which control the actin cytoskeleton in distinct ways ❚ Another major role is the regulation of gene expression ❚ Activity is controlled by RhoGEF and RhoGAP proteins ❚ Cell movement, axonal guidance, cytokinesis, and morphogenetic processes involving changes in cell shape and polarity
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Activation of RhoGEFs By Extracellular Signals
Copyright (c) by W. H. Freeman and Company
Structure of protooncogene Vav (DH domain)
Copyright (c) by W. H. Freeman and Company
Translocation of RhoGEF
Copyright (c) by W. H. Freeman and Company
Effectors of Rho Proteins
Copyright (c) by W. H. Freeman and Company
Effectors of Rac and Cdc42 Proteins
Copyright (c) by W. H. Freeman and Company
Function of Rho Family Proteins ❚ The function of of the Rho family was first demonstrated in yeast: budding and cell polarity ❚ In mammals, the function of Rac was the first to be clarified: Rac1, in addition to two other cytosolic proteins p47phox and p67phox, were shown to be required for the activation of NADPH oxidase of phagocytic cells ❚ The function of mammalian Rho was elucidated by use of an exoenzyme named C3 (an inhibitor): in cytoskeletal control
Copyright (c) by W. H. Freeman and Company
Stress fiber formation and focal adhesion
Lamellipodial extension and membrane ruffles
Filopodia or microspikes Copyright (c) by W. H. Freeman and Company
Reorganization of the Actin Cytoskeleton ❚ Rho: Actin stress fibers: bundles of actin filaments that traverse the cell and are linked to theextracellular matrix through focal adhesions ❚ Rac: Lamellipodia: thin protrusive actin sheets that dominate the edges of cultured fibroblasts and many migrating cells; membrane ruffles observed at the leading edge of the cell result from lamellipodia that life up off the substratum and fold backward ❚ Cdc42: Filopodia: fingerlike protrusions that contain a tight bundle of long actin filaments in the direction of the protrusion. They are found primarily in motile cells and neuronal groath cones. Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Rab ❚ The first Rab genes discovered were the YPT1 and SEC4 genes in yeast ❚ Number at least 30 ❚ Play key roles in the secretory and endocytic pathways ❚ Located in distinct cellular compartments ❚ Facilitate the formation of vSNARE/tSNARE complexes, which are integral components of vesicle trafficking ❚ It is proposed that Rabs act by recruiting specific docking factors (Exocyst, Rabaptins) from the cytosol to facilitate pairing of the SNAREs ❚ Transport vesicles carry RabGTP. After membrane fusion, GTP hydrolysis converts to RabGDP Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
ARF ❚ The first ARF was discovered as a stimulatory cofactor required for the ADPribosylation of the Gαs by cholera toxin in 1984 ❚ Three classes of ARF ❚ Critical components of several vesicular trafficking pathways ❚ ARFGEF: Sec7 domain ❚ ARFGAP ❚ Relative lack of information about the class II (ARF 4 and 5) and III (ARF6) ARFs ❚ Interacts with PLD, PIP2, coatomers, arfaptin Copyright (c) by W. H. Freeman and Company
ER to Golgi and intraGolgi transport
Formation of a transport vesicle begins when activated ARFGTP associates with the cytoplasmic surface of a donor membrane. How the initiation site is identified remains unknown. Activated ARF interacts with a coat protein, one of seven in the coatomer complex. Recruitment of multiple ARF molecules followed by coatomers causes membrane deformation and budding. Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Ran ❚ Rasrelated nuclear protein ❚ Play a central role in protein and RNA trafficking in and out of the nucleus ❚ Macromolecules travel in and out of the nucleus through nuclear pore complexes (NPCs) and utilize different receptors and carriers. ❚ Almost all the receptors interact with GTPRan and are regulated by the Ran GTPase cycle ❚ Ran functions to trigger the assembly or disassembly of transport complexes ❚ RanGEF in nucleus and RanGAP in cytoplasm Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Copyright (c) by W. H. Freeman and Company
Signaling through small GTPases ❚ ❚ ❚ ❚ ❚
Ras: Raf/MEK/ERK, cell growth (gene expression) Rho: Actin cytoskeleton and gene expression Rab: Secretory and endocytic pathways (Vesicle trafficking) ARF: Vesicle budding Ran: Nucleocytoplasmic Transport (and microtubule organization)
Copyright (c) by W. H. Freeman and Company
Related Documents
Cell Biol Lecture-1
October 2019 14
Cell Biol Lecture-2
October 2019 13
Lecture2
June 2020 14
Lecture2
November 2019 20
Lecture2
July 2020 10