BIOL201 Lecture Notes - Lecture 9: Insulin Receptor, Autocrine Signalling, Paracrine Signalling
Biology 201 Dr. Torah Kachur
1
Lecture 9 – Cell Signaling
Introduction
Cells in multicellular organisms must talk to each other, we have seen how they can use
intercellular junctions like gap junctions to share signals in a common cytoplasm but how do
autonomous cells communicate? We will look at several examples of how cells can send and
receive signals and transduce that message into a meaningful cellular response.
Objectives:
✓ Define: autocrine, endocrine, paracrine, receptor, ligand, transmembrane domain, ligand
binding domain, kinase, phosphatase, G-protein, cross-phosphorylation, amplification,
integration, second messenger, cAMP, Rhodopsin
✓ Explain the difference between endocrine, paracrine and autocrine signaling and be able to
outline why each strategy is used
✓ Describe how receptor-ligand specificity is obtained
✓ Outline the basic similarities and differences between G-protein and kinase linked receptors
✓ Why are second messengers useful in the cell?
✓ Explain why different second messengers are used for different signals
✓ Describe, in detail, how IP3 is used in a second messenger and outline the process where this
is used
✓ Explain how a cell accomplishes a desired cellular response using different signaling
cascades
Lecture Outline
1. The Message
Types of chemical messengers (Figure 14.1, Page 393)
1. Endocrine signals – act over a long distance and are distributed through the blood stream
• Example: Insulin – (page 417)
2. Paracrine signals – act over short distances and are
released locally
• Example: Epidermal Growth factor – (page
408, Figure 14-16)
3. Autocrine signals –
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Biology 201 Dr. Torah Kachur
2
2. The Receptor (page 393-394)
• Receptors are almost always transmembrane proteins in the cellular membrane (the
exception: steroid hormone receptors)
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