the nerve cell transmits electrical signals to target cells

1
Signal Transduction
2
Signal Transduction

• What is it?
• Why do we care about it?
• How does it work?

3
Types of Signaling

• Cell-to-cell signaling happens when a cell
  secretes a molecule
• There are 3 types of signaling
• Synaptic
• Paracrine
• Endocrine

4
Synaptic Signaling

• The nerve cell transmits electrical signals to
  target cells using chemical signals called
  neurotransmitter.

5
Paracrine Signaling

• Signaling molecules that affect cells in the
  immediate vicinity.

6
Endocrine Signaling

• Endocrine cells secrete hormones into the
  bloodstream.

7
Types of Signaling

• Synaptic nerve cells transmitting an electrical
  signal
• Paracrine close signaling
• Endocrine distant signaling

8
Signaling Mediated by Secreted Molecules

• Different cells can respond differently to the
  same chemical signal.

9
What Happens Once the Signal is Received by the
Cell?

• Cascade of signals resulting in a cellular
  response.

10
Role of Enzymes in Signal Transduction

• What is an enzyme?
• Most proteins involved in the signal cascade are
  enzymes that are activated by addition of a
  phosphate.
• These same proteins are inhibited by removal of a
  phosphate.

Phosphorylated and activated
Dephosphorylated and inhibited
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Direct Phosphorylation
12
Direct Phosphorylation

• Serine/threonine kinases
• Tyrosine kinases

P
P
P
13
Indirect Phosphorylation GTP Binding
14
Signal Integration
15
Signaling via G-Protein-Linked Cell Surface
Receptors
16
G-Protein-Linked Cell Surface Receptors
17
Trimeric G Proteins
18
G-Protein Activation of Enzyme
19
G-Protein Activation of Enzyme
20
Signaling via Enzyme-Linked Receptors
21
Review

• 3 types of signaling
• Enzymes are activated by
• Enzymes are inhibited by
• 2 types of receptors
• 3 types of functional proteins
• Why is Signal Transduction important?