molecular biology

2. Secondary messengers

3. Secondary Messengers
Target molecule inside the cell

4. They greatly amplify the strength of signal,
causing some changes in the activity of the cell.
Components cell signaling pathways.
They are short lived intracellular signalling
molecules

5. EARL WILBUR
SUTHERLAND JR.
1971

6. Cyclic
Nucleotides
Membrane
lipid
derivatives
Ca2+
Nitric oxide
/carbon
mono oxide
Four classes
of
secondary
messengers

8. EX. Of cAMP Action – Adrenaline, glucagon, LH

9. cGMP secondary messenger:
1 nitric oxide (NO)
2 the response of rods of the retina to light

10. PHOSPHATIDYLINOSITOL (IP)
_ Phospholipid
&
Minor component
Eukaryotic cell
membrane

11. Phosphatidylinositol
(Derived)
Intracellular enzyme PHOSPHOLIPASE C
(hydrolyzes)
PIP2
which is found in the inner layer of plasma
membrane.
Hydrolysis of PIP2 yeilds two products :
 Diacylglycerol (DAG)
 Inositol-1,4,5 – triphosphate (IP3)

12. Diacylglycerol stimulates protien kinase C activity by greatly
increasing the affinity of the enzyme for calcium ions.
Protien kinase C phosphorylates specific serine and threonine
residues in target protiens .
Target protiens include calmodulin, the glucose
transporter,cytochrome P450 etc.

13. This soluble molecule Diffuses
through the cytosol and binds to
the recptors on the endoplasmic
reticulum causing release of
calcium ions (ca2+ ) into the
cytosol.
The rise in the intracellular
calcium triggers the response.

15. Many cells respond to extracellular stimuli by altering their intra
cellular calcium concentration
Ca++ secondary messenger in Two ways :
• binds effector molecule ,such as enzyme , activating it.
• binds intermediatory cytosolic calcium binding protien
Calmodulin cause contraction of smooth muscles
ACTIVATED
CALMODULIN

16. affect nearby cells .
It activates soluble guanylyl cyclase,
which when activated produces another
second messenger,cGMP
NO
Secondary
messenger
FREE
RADICAL
PLASMA MEMBRANE

17. NO
SYNTHESIZED
BY NO SYNTHETASE

19. Cell Signaling

20. CELL SIGNALING is about
communication between
different groups of cells and
tissues. How one group of
cells informs the another
group of cells what to do.
SIGNAL TRANSDUCTION
refers to how the presence of
an extracelluar signal can
produce a change in the
intracellular state of the cell
without the initial signal
crossing the membrane.

21. During development cells differentiate to adopt
specialized roles.
Cells need to know whether to live, die, or divide
Neurotransmission
Regulation of metabolism
Contraction –expansion

24. AUTOCRINE signals target the cell itself
PARACRINE signals target cells in the
vicinity of emitting cell
ENDOCRINE signals target distant cells
JUXTACRINE cells target adjacent cells

29. CELL ADHESION

30. Cell adhesion Ability
OR

31. Helps stick to each other and to the
surroundings
CELL ADHESION
MOLECULES

32. Cell adhesion is
involved in
stimulating
signals that
regulate

33. Changes in cell adhesion can be the defining event in a
wide range of diseases including

35. CADHERIN
IMMUNOGLOBULIN
SUPER FAMILY CELL
ADHESION MOLECULES
SELECTIN INTEGRIN
CELL
ADHESION
MOLECULES

36. Cell adhesion molecules Have following functions :
 INVOLMENT IN INFLAMMATION
 TUMEROGENISIS
 ESTBLISHMINT OF THE BLOOD –BRAIN BARRIER
 INVOLMENT IN LYMPHOCYTE HOMING
 IN REGULATION OF APOPTOSIS

37. CELL DEATH

44. CELL REGULATION

46. Are those which control the changes necessary for cell
division
They include :
 CYCLINS
 CYCLIN-DEPENDENT KINASES (CDKS)
 POLO-LIKE KINASES

48. CELL ADAPTATION

51. Altered cell surface receptor binding
Alterations in signal for protien synthesis
Synthesis of new protiens by the target cell such as
heat shock protiens

53. (Lippincott’s Illustrated Reviews) Nalini Chandar, Susan Viselli - Cell
and Molecular Biology (Lippincott’s Illustrated Reviews) -Lippincott
Williams & Wilkins (2010)
Bruce Alberts, Dennis Bray, Karen Hopkin, Alexander D Johnson,
Julian Lewis, Martin Raff, Keith Roberts, Peter Walter-Essential Cell
Biology, 4th Edition
Molecular Biology of the Cell - 4th edition alberts