The presentation aims to provide basics of bio signalling to the viewers. The various mechanisms of signalling in cells along with the details about G signalling are covered under this ppt.

2. www.biosignaling.com

3. Introduction
 T he ability of cells to receive and act on signals from
beyond the plasma membrane is fundamental to life
and is termed bio signaling.

4. Introduction
 T he ability of cells to receive and act on signals from
beyond the plasma membrane is fundamental to life
and is termed bio signaling.
www.fpnotebook.com

5. Introduction
 T he ability of cells to receive and act on signals from
beyond the plasma membrane is fundamental to life
and is termed bio signaling.
yaolab.stanford.edu

6. Introduction
 T he ability of cells to receive and act on signals from
beyond the plasma membrane is fundamental to life
and is termed bio signaling.
 In these cases, signals represent information that is
detected by specific receptors and converted into
cellular response which involves chemical
processes.
Signals
(Light,touch,ho
rmones,antigen
s,nutrients,neu
rotransmitters)
Recepto
rs
Cellular
Respons
e

7. Signal transducing system
 Salient features
(1) Specificity and high affinity
www.motifolio.com

8. Signal transducing system
 Salient features
(2) Cooperativity
meyerbio1b.wikispaces.com

9. Signal transducing system
 Salient features
(3) Amplification by enzyme cascade
agbioinc.com

10. Signal transducing system
 Salient features
(4) Integration : Ability of the system to receive
multiple signals , integrate them and produce
unified response most appropriate to the
needs of the cell.

11. Signal transducing system
 Salient features
(4) Integration : Ability of the system to receive
multiple signals , integrate them and produce
unified response most appropriate to the
needs of the cell.
(5) Desensitization : When a signal is present
continuously, desensitization of the receptor
system occurs and when the signal falls
below threshold, the system gains sensitivity
again.

12. Types of signal transducing
system
(1) Gated ion channel
Opens or closes in response to concentration of signal ligand (S)
or membrane potential.
www.clker.com

13. Types of signal transducing
system
(2) Receptor enzyme
Ligand binding to extracellular domain stimulates enzyme
activity in intracellular domain.
www.nature.com
Img : Binding of a ligand to receptor tyrosine kinases (RTKs)

14. Types of signal transducing
system
(3) Steroid receptor
Steroid binding to a nuclear receptor protein allows the
receptor to regulate the expression of specific genes.
users.rcn.com

15. Types of signal transducing
system
(4) Serpentine receptor
External ligand binding to receptor (R) activates an
intracellular GTP-binding protein (G), which regulates an
enzyme (Enz) that generates an intracellular second
messenger, X.
2012.igem.org

16. Types of signal transducing
system
(5) Receptor with no intrinsic enzyme activity(membrane
proteins)
Receptors that lack enzymatic activity but attract and
activate cytoplasmic enzymes that act on downstream
proteins, either by directly converting them to gene-regulating
proteins or by activating a cascade of enzymes that finally
activates a gene regulator.
(6) Adhesion receptor
Receptors (adhesion receptors) that interact with
macromolecular components of the extracellular matrix (such
as collagen) and convey to the cytoskeletal system
instructions on cell migration or adherence to the matrix.

17. G protein signaling
 Guanosine nucleotide binding protein is a
heterotrimer (with 3 different units) : alpha ,beta
and gamma.
 The alpha unit is bound to GDP and has high
affinity for beta and gamma units.
 The human genome encodes more than 1000
GPCR (G protein coupled receptors) that
transduce messages as light ,touch or hormones.
sitemaker.umich.edu

18. http://www.youtube.com/watch?v=wC2_7R
or3qY

19. careerrocketeer.com
****Lehninger Principles of Biochemistry
David L. Nelson (University of Wisconsin-Madison) ,
Michael M. Cox (University of Wisconsin-Madison)
***Sixth Edition ©2013
***The Regulator of G Protein Signaling Family
Annual Review of Pharmacology and Toxicology
Vol. 40: 235-271
Luc De Vries Bin Zheng Thierry Fischer Eric Elenko and
Marilyn G. Farquhar

20. corelaborate.psesd.