Discovery of G-proteins and the role of these proteins in signal transduction
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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.

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Wen-Chun Shaw Dr. VanKley Scientific Discovery

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Wen chun shaw dr vankley scientific discovery

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??


G protein coupled receptor signaling

G-protein coupled receptor signaling

(A)

(B)

(C)

(D)


G protein coupled receptor

G-protein coupled receptor


Gpcr and disease

GPCR and Disease


Cholera

Cholera

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.


Wen chun shaw dr vankley scientific discovery

  • The bacterium discovered by 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

  • 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

  • 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.


Wen chun shaw dr vankley scientific discovery

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


Wen chun shaw dr vankley scientific discovery

5. Skin cells, this causes darker pigment.

6. Bone cells, it causes weakness and fractures.

7. Hormone-producing cells

the mutation causes

the release of excess

hormones


Martin rodbell

Martin Rodbell


The nobel prize in physiology or medicine 1994

The Nobel Prize in Physiology or Medicine 1994

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


Wen chun shaw dr vankley scientific discovery

  • 1925 --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


Wen chun shaw dr vankley scientific discovery

  • 1950 --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


Wen chun shaw dr vankley scientific discovery

  • 1967-68 --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


Wen chun shaw dr vankley scientific discovery

  • 1985-89 --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

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.


Wen chun shaw dr vankley scientific discovery

  • 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

  • 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


Second messenger

Second Messenger

  • 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.


Wen chun shaw dr vankley scientific discovery

  • 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.


Wen chun shaw dr vankley scientific discovery

  • Rodbell realized that his isolated fat cells were the perfect medium for further investigation of the mechanism of hormone action.


Metabolism of isolated fat cells

Metabolism of Isolated Fat Cells

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


Comparison between tissue and cells

Comparison between tissue and Cells

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


Different hormone act on the fat cells

Different hormone act on the fat cells


Wen chun shaw dr vankley scientific discovery

  • Finally, Martin Rodbell create a system to analyze hormone action in individual fat cells.

  • Even, different hormone can be used in this system.


Wen chun shaw dr vankley scientific discovery

  • Many researchers began using Rodbell's method, making "The Metabolism of Isolated Fat Cells" one of the most widely cited in the field.


Demonstration of distinct hormone receptor

Demonstration of distinct Hormone Receptor

  • 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.


Wen chun shaw dr vankley scientific discovery

  • Because of the experimental complexity of studying the multi-receptor adenylate cyclase system in rat adipocytes. Rodbell turned his attention to the glucagon-sensitive adenylate cyclase system in liver.


Informational processing the concept of transduction

Informational processing: the concept of transduction


Glucagon sensitive adenylate cyclase system in liver

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

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


Wen chun shaw dr vankley scientific discovery

  • GTP could reverse the binding process almost one thousand times faster than ATP

  • This GTP, he found, stimulated the activity in the guanine nucleotide protein (later called the G-protein) in the cell


Gtp hydrolysis

GTP Hydrolysis

  • 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

  • a-subunit uniquely

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

  • g subunits.


Wen chun shaw dr vankley scientific discovery

β

α

γ


The future of gpcr

The future of GPCR


Valuable g protein coupled recptor

Valuable G-protein coupled Recptor

GPCRs are good drug targets

50% of subscription drugs interact with GPCR

  • Hypertension

  • Stomach ulcers

  • Migraine

  • Allergies


Wen chun shaw dr vankley scientific discovery

GPCRs in disease states

  • Disease states associated with GPCR mutations

  • Rhodopsin receptor

retinitis pigmentosa

  • Vasopressin V2

nephrogenic diabetes

  • Glucagon

diabetes, hypertension


Reference

Reference

  • 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


Wen chun shaw dr vankley scientific discovery

  • 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


Wen chun shaw dr vankley scientific discovery

  • 5'-Guanylylimidodiphosphate, A Potent Activator Adenylate Cyclase Systems in Eukaryotic Cells, Proc. Nat. Acad. Sci. USA Vol. 71, No. 8, pp. 3087-3090, August 1974, Constantine Londos, Yoram Salomon, And Martin Rodbell


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