CELL SIGNALING BY MOIN KHAN HUSSAIN

1. CELLULAR PROCESS
PRESENTATION
BY:-MOIN KHAN HUSSAIN
UID:-14BBT1129

2. Cell Signaling
A. Types of Cell Signaling
B. Intracellular Receptor Signaling:
Steroid Hormones
C. Cell Surface Receptors: Types
D. Cell Surface Receptors: G-protein
linked receptors

3. A. Types of Cell
Signaling
• Direct cell-cell signaling vs.
signaling via secretion

4. A. Types of Cell
Signaling
• Cell surface receptors vs.
Intracellular receptors

5. A. Types of Cell Signaling
• Three forms of signaling by secreted
molecules
– Paracrine
– Synaptic
– Endocrine

6. Endocrine further divide
into two part:-

7. A. Types of Cell
Signaling
• Gap junctions

8. A. Types of Cell
Signaling
• The same signal can produce different
effects in different cells

9. A. Types of Cell
Signaling
• Types of Signals based on
Where they Bind
– To an intracellular receptor:
e.g. Steroid hormones
– To a cell-surface receptor: G-protein linked,
enzyme-linked, or ion channel-linked

10. B. Intracellular Receptor
Signaling: Steroid Hormones
• Overview of Steroid Hormone
Action:
– Steroid hormone (small, hydrophobic) is
secreted by glandular cells and released
into bloodstream (usually transported
via shuttle proteins)
– The hormone enters the cytoplasm of
cells
– In the cytoplasm of target cells, the
hormone binds to steroid hormone
receptor protein

11. B. Intracellular Receptor
Signaling: Steroid Hormones
• Overview of Steroid . . . (cont.):
– The steroid-receptor conplex is
translocated into the nucleus, where it
activates the transcription of the
primary response genes
– Transcription of the primary response
genes, followed by translation, results in
the production of primary response
proteins

12. B. Intracellular Receptor Signaling:
Steroid Hormones
• Overview of Steroid . . . (cont.):
– The primary response proteins usually inhibit
further transcription of their own genes, and
they may activate transcription of secondary
response genes.

13. C. Cell Surface Receptors:
Types
• Three known classes of cell surface
receptors
– Ion channel-linked, G-protein-linked, Enzyme-linked
– An activated cell-surface receptor triggers a
phosphorylation cascade

16. D. Cell Surface Receptors:
G-protein linked receptors
• Largest family of cell surface receptors
– Different ones respond to a wide variety of mediators including
different hormones, neurotransmitters, local mediators
– Examples: Receptors to epinephrine, acetylcholine, serotonin

17. B. G-linked Receptors
• What do G-protein receptors do?
– G-protein receptors activate trimeric G-protein
– Activated G-protein alters the cellular
concentration of a “second messenger”: usually
cyclic AMP or Ca2+
– The second messenger activates a protein
kinase enzyme
– The protein kinase phosphorylates another
enzyme and alters its activity

19. B. G-linked Receptors
• Trimeric G-proteins disassemble when
activated
– Three chains: a, b, and g
 a chain binds and hydrolyzes GTP
 b & g chains form a tight complex bg that
anchors G-protein to the plasma membrane

20. B. G-linked Receptors
• Action of epinephrine on glycogen
metabolism
– Epinephrine (adrenaline) is released from the
adrenal gland in times of stress. It has two
overall actions on glycogen metabolism: it
inhibits glycogen synthesis, and it promotes
glycogen breakdown
– This is mediated by a protein phosphorylation
cascade

21. SUMMARY
1. Types of Cell Signaling
2.Intracellular Receptor Signaling:
Steroid Hormones
3.Cell Surface Receptors: Types
4.Cell Surface Receptors: G-protein
linked receptors

22. THANK YOU!!!
MOIN KHAN
HUSSAIN
UID:-14BBT1129