CELL SIGNALING

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 Ca
2+
–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, andg
achain binds and hydrolyzesGTP
b& gchains form a tight complex bgthat
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