Discovery of G-proteins and the role of these proteins in signal transduction
Download
1 / 44

Wen-Chun Shaw Dr. VanKley Scientific Discovery - PowerPoint PPT Presentation


  • 130 Views
  • Uploaded on

Discovery of G-proteins and the role of these proteins in signal transduction Martin Rodbell & Alfred G. Gilman. Wen-Chun Shaw Dr. VanKley Scientific Discovery. What is G-protein??. G-protein coupled receptor signaling. (A). (B). (C). (D). G-protein coupled receptor. GPCR and Disease.

loader
I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.
capcha
Download Presentation

PowerPoint Slideshow about ' Wen-Chun Shaw Dr. VanKley Scientific Discovery' - carlyn


An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript

Discovery of G-proteins and the role of these proteins in signal transduction Martin Rodbell & Alfred G. Gilman

Wen-Chun Shaw

Dr. VanKley

Scientific Discovery


What is g protein

What is G-protein?? signal transduction


G protein coupled receptor signaling
G-protein coupled receptor signaling signal transduction

(A)

(B)

(C)

(D)


G protein coupled receptor
G-protein coupled receptor signal transduction


Gpcr and disease

GPCR and Disease signal transduction


Cholera
Cholera signal transduction

Cholera is caused by a comma-shaped bacterium, Vibrio cholerae, which is ingested in contaminated water and food. The bacteria multiply enormously in the intestine, where epithelial cells allow fluid to leak into the

intestine with intense diarrhoea as a result. Cholera is endemic in India and other parts of the third world.


  • The bacterium discovered by signal transduction Robert Koch in 1884, can be killed by antibiotics, but the disease is caused by a bacterial toxin, which irreversibly activates the G proteins of epithelial cells in the intestine. This results in an often life-threatening loss of water and salts. From Koch's discovery of the cholera bacterium in 1884 it took researchers about 100 years to expose the real cause of the disease - the effect of the bacterial toxin on G proteins


Inherited night blindness
Inherited Night Blindness signal transduction

  • Scientists have found a G-protein defect in one type of inherited night blindness. Persons with this condition have a mutation in the gene that codes for the G-protein found in the eye's rod cells. Scientists believe that this defective G-protein is overactive. It stays turned on more than it normally would, and the person can't see well at low light levels.


Mccune albright syndrome
McCune Albright Syndrome signal transduction

  • named for the two physicians who described it over 50 years ago.

  • They reported a group of children, most of them girls, with an unusual pattern of associated abnormalities.

  • In this disease, a mutation occurs sometime after conception, affecting only some of the body's cells.


4. Scientists have found that the mutation affects the same G-protein involved in cholera. This G-protein gets active continuously.


5. Skin cells, this causes darker pigment. G-protein involved in cholera. This G-protein gets active continuously.

6. Bone cells, it causes weakness and fractures.

7. Hormone-producing cells

the mutation causes

the release of excess

hormones


Martin rodbell

Martin Rodbell G-protein involved in cholera. This G-protein gets active continuously.


The nobel prize in physiology or medicine 1994
The Nobel Prize in Physiology or Medicine 1994 G-protein involved in cholera. This G-protein gets active continuously.

  • "for their discovery of G-proteins and the role of these proteins in signal transduction in cells"


  • 1925 G-protein involved in cholera. This G-protein gets active continuously. --born in Baltimore, Maryland, December 1st, son of Milton W. Rodbell, a grocery store owner

  • 1943 -1943 --enters The Johns Hopkins University; studies biology and French literature

  • 1944-1946 --education interrupted: drafted into the Navy; serves as a radio operator in the South Pacific, China, the Philippines, and Korea

  • 1949 --receives B.S. in biology, The Johns Hopkins University

  • 1949-50 --post-graduate study in chemistry at Hopkins

  • 1950 --marries Barbara Charlotte Ledermann; four children; seven grandchildren


  • 1950 G-protein involved in cholera. This G-protein gets active continuously. --moves to Seattle and enters Ph.D. program in biochemistry, University of Washington

  • 1954 --completes Ph.D. thesis, Lecithin Metabolism in the Liver, under Donald H. Hanahan

  • 1954-56 --postdoctoral position at U Illinois; research associate in biochemistry

  • 1956-61 National Heart Institute, NIH as research chemist in Laboratory of Cellular Physiology and Metabolism

  • 1960-61 --NIH-sponsored training at University of Brussels, Belgium, and Leiden University


  • 1967-68 G-protein involved in cholera. This G-protein gets active continuously. --Institute of Clinical Biochemistry, University of Geneva, professor and acting director

  • 1971 --publishes core of work on G-proteins in a series of articles in the Journal of Biological Chemistry

  • 1981-83 --Department of Clinical Biochemistry, University of Geneva, visiting professor


  • 1985-89 G-protein involved in cholera. This G-protein gets active continuously. --National Institute of Environmental Health Sciences, Chapel Hill, North Carolina, scientific director

  • 1987 --inducted into the National Academy of Sciences; receives Richard Lounsbery Award.

  • 1989-94 --NIEHS, Section on Signal Transduction, chief

  • 1994 --retires; becomes NIH Scientist Emeritus; shares Nobel Prize with Alfred G. Gilman (announced Oct. 10, awarded Dec. 10)

  • 1998 --dies at Chapel Hill, December 7


The concept of receptor
The concept of receptor G-protein involved in cholera. This G-protein gets active continuously.

Paul Enrlich (1854-1915).

his work on immunity

for which he was awarded

the Nobel Prize for Medicine

/Physiology in 1908

the development of selective

chemotherapeutic agents,

especially against syphilis and

the foundation of haematology

through his use of new dye staining techniques.


  • In his voluminous thesis, Ehrlich proposed that the reactions between aniline dyes and cells was a chemical rather than a physical interaction, that there was a specificity between the dye and the cell or tissue it stains, and further that the chemical structure of the dye molecule defined its solubility and ability to attach (bind) to cells. As others have noted , here was the seed of a receptor theory.

    Lock and Key


Isolation of single fat cells
Isolation of single Fat Cells reactions between aniline dyes and cells was a chemical rather than a physical interaction, that there was a specificity between the dye and the cell or tissue it stains, and further that the chemical structure of the dye molecule defined its solubility and ability to

  • At that time, the only test medium available was crude chunks of fat tissue. No one can study the effect of hormones on individual cells.

  • Because fat floats, Rodbell first put the minced tissue in a liquid and then treated the floating cells with a substance called collagenase. Then, fat cells flaoted to the surface ,and the stromal-vascular cells (capillary, endothelial, mast, macrophage, and epithelial cells)were sedimented.


Isolation of single fat cells1
Isolation of single Fat Cells reactions between aniline dyes and cells was a chemical rather than a physical interaction, that there was a specificity between the dye and the cell or tissue it stains, and further that the chemical structure of the dye molecule defined its solubility and ability to


Second messenger
Second Messenger reactions between aniline dyes and cells was a chemical rather than a physical interaction, that there was a specificity between the dye and the cell or tissue it stains, and further that the chemical structure of the dye molecule defined its solubility and ability to

  • At that time, scientists knew that the adrenal gland produces epinephrine travels to body's cells and causes an increase in blood sugar. Let body have energy to react to stressful situations. But no one understood exactly how this hormone produced such an effect.


  • In the late 1950s, Sutherland investigated the effect of epinephrine on liver tissue. He discovered that the hormone—the "first" messenger—stimulates formation of a "second messenger" within cells. It is this second substance, cyclic adenosine monophosphate (cAMP), that stimulates the breakdown of stored carbohydrate into sugar.



Metabolism of isolated fat cells
Metabolism of Isolated Fat Cells perfect medium for further investigation of the mechanism of hormone action.

  • Incubate isolated fat cells with Glucose-U-14C.


Comparison between tissue and cells
Comparison between tissue and Cells perfect medium for further investigation of the mechanism of hormone action.

Group(I) Unfed, ON Group(II) fed


Different hormone act on the fat cells
Different hormone act on the fat cells perfect medium for further investigation of the mechanism of hormone action.




Demonstration of distinct hormone receptor
Demonstration of distinct Hormone Receptor Metabolism of Isolated Fat Cells" one of the most widely cited in the field.

  • The various hormones were tested at maximal and submaximal concentrations alone or combinedwith the other hormones. Synergy was seen with some combinations, but, most importantly, additivity of response was not obtained with maximal concentrations of the hormones. Although not completely proof,they argued that it is likely that the fat cell cyclase system consists of multiple receptors interacting with a common catalytic unit.



Informational processing the concept of transduction
Informational processing: the concept of transduction multi-receptor adenylate cyclase system in rat adipocytes. Rodbell turned his attention to the glucagon-sensitive adenylate cyclase system in liver.


Glucagon sensitive adenylate cyclase system in liver
Glucagon-sensitive adenylate cyclase system in liver. multi-receptor adenylate cyclase system in rat adipocytes. Rodbell turned his attention to the glucagon-sensitive adenylate cyclase system in liver.

  • Chromatography of 125I-Glucagon

  • Measurements of Adenyl Cyclase Activity-measured by the conversion of 32P-ATP to cyclic 5’-AMP

  • This system can investigate both the nature of the glucagon receptor and the relationship between hormone binding and hormonal activation of adenylate cyclase.


The actions of gtp and glucagon on liver cyclase
The actions of GTP and Glucagon on Liver Cyclase multi-receptor adenylate cyclase system in rat adipocytes. Rodbell turned his attention to the glucagon-sensitive adenylate cyclase system in liver.

  • Rodbell discovered that ATP could reverse the binding action of glucagon to the cell receptor and thus dissociate the glucagon from the cell altogether.



Gtp hydrolysis
GTP Hydrolysis times faster than ATP

  • A few months later, they found that Gpp(NH)p caused the enzyme’s activity to “take off’ to an extent not even seen.


General characteristics of guanine nucleotide action
General Characteristics of Guanine Nucleotide Action times faster than ATP

  • a-subunit uniquely

  • capable of binding and degrading GTP and a tightly knit complex of b and

  • g subunits.


β times faster than ATP

α

γ


The future of gpcr

The future of GPCR times faster than ATP


Valuable g protein coupled recptor
Valuable G-protein coupled Recptor times faster than ATP

GPCRs are good drug targets

50% of subscription drugs interact with GPCR

  • Hypertension

  • Stomach ulcers

  • Migraine

  • Allergies


GPCRs in disease states times faster than ATP

  • Disease states associated with GPCR mutations

  • Rhodopsin receptor

retinitis pigmentosa

  • Vasopressin V2

nephrogenic diabetes

  • Glucagon

diabetes, hypertension


Reference
Reference times faster than ATP

  • www.nobel.se

  • http://history.nih.gov/

  • http://profiles.nlm.nih.gov/

  • Metabolism of Isolated Fat Cells, Martin Rodbell, J. of Biol. Chem., , Vol.239, No. 2, February 1964

  • The Glucagon-sensitive Adenyl Cyclase System in Plasma Membranes of Rat Liver, J. OF Biol Chem., Vo1.246. No.6, pp. 1857-1869,1971, Lutz Birnbaumer, Stephen L. Pohl, and Martin Rodbell


  • The Fat Cell Adenylate Cyclase System, J. OF Biol Chem.,Vol 254 ,No.18, pp8927-8931, 1979, Dermot M. F. Cooper, Werner Schlegel, Michael C. Lin, end Martin Rodbell

  • The role of hormone receptors and GTP-regulatory proteins in membrane transduction, Nature, Vol. 284, No. 575 1, pp. 17-22. March 6 1980, Martin Rodbell



ad