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

1
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

2
What is G-protein??
3
G-protein coupled receptor signaling
(A)
(B)
(C)
(D)
4
G-protein coupled receptor
5
GPCR and Disease
6
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.
7

• 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

8
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.

9
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.

10

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

11

• 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
12
Martin Rodbell
13
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"

14

• 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

15

• 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

16

• 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

17

• 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

18
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.

19

• 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

20
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.

21
Isolation of single Fat Cells
22
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.

23

• In the late 1950s, Sutherland investigated the
  effect of epinephrine on liver tissue. He
  discovered that the hormonethe "first"
  messengerstimulates 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.  

24

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

25
Metabolism of Isolated Fat Cells

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

26
Comparison between tissue and Cells
Group(I) Unfed, ON Group(II) fed
27
Different hormone act on the fat cells
28

• Finally, Martin Rodbell create a system to
  analyze hormone action in individual fat cells.
• Even, different hormone can be used in this
  system.

29

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

30
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.

31

• 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.

32
Informational processing the concept of
transduction
33
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.

34
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.

35

• 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

36
GTP Hydrolysis

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

37
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.

38
ß
a
?
39
The future of GPCR
40
Valuable G-protein coupled Recptor

• GPCRs are good drug targets
• 50 of subscription drugs interact with
  GPCR
• Hypertension
• Stomach ulcers
• Migraine
• Allergies

41
(No Transcript)
42
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

43

• 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

44

• 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