Ligands, Receptors, Signaling Pathways Lecture 1

Question 1

True or False: Almost all disease processes and their treatments are influenced by ligands, receptors, intracellular signaling, pathway interactions and ultimately effects on gene expression.

Answer 1

True

Question 2

A _____ is a molecule that binds tightly and specifically to another molecule.

Answer 2

Ligand

Question 3

True or False: Ligands are not specific to certain receptors that they bind to.

Answer 3

False

Question 4

Describe the general scheme of ligands, receptors, and signaling pathways.

Answer 4

1. A ligand is present in the extracellular fluid
2. The ligand binds to a protein cellular receptor
3. The ligand-receptor binding activates intracellular signaling pathways
4. Intracellular signaling pathways activate gene expression including transcription and translation
5. The proteins produced in response to the ligand cause a biological response

Question 5

What are the three general mechanisms of cell communication?

Answer 5

1. Endocrine
2. Paracrine
3. Autocrine

Question 6

______ cell communication consists of hormones that serve as ligands that are synthesized and released from one organ. They travel through _____ and bind to a specific receptor of the target tissue _____ from the site of synthesis.

Answer 6

• Endocrine
• Blood
• Distant

Question 7

______ cell communication consists of ligands that are synthesized and released from a tissue in close proximity to the target tissue.

Answer 7

Paracrine

Question 8

How does autocrine cellular communication work?

Answer 8

Ligands are synthesized and released from a cell, and the cell of origin responds to its own ligands

Question 9

True or False: Cells expressing the gene encoding the protein receptor as well as those not expressing the gene and without a receptor can respond to a certain ligand.

Answer 9

False, only cells expressing the gene encoding the protein receptor for the ligand can respond to the ligand

Question 10

Where are hydrophilic receptors localized? Hydrophobic receptors such as steroid hormones?

Answer 10

• The plasma membrane

- cytoplasm and nucleus of cells

Question 11

A structure on the plasma membrane of a cell or inside a cell that selectively binds a ligand

Answer 11

Receptor

Question 12

An enzyme that transfers a phosphate group from ATP to a substrate

Answer 12

Kinase

Question 13

Give two examples of receptor tyrosine kinases

Answer 13

1. Epidermal Growth Factor Receptors

2. Insulin Receptor

Question 14

Describe the three domains of receptor tyrosine kinases.

Answer 14

1. Ligand Binding Domain: extracellular, binds to ligands
2. Transmembrane domain: Hydrophobic, spans the plasma membrane
3. Cytoplasmic domain: contains kinase

Question 15

Receptor tyrosine kinases are ______-____ proteins.

Answer 15

Multi-domain

Question 16

What are the three domains of receptor tyrosine kinases?

Answer 16

1. Extracellular (ligand binding)
2. Transmembrane Domain (plasma membrane)
3. Intracellular Domain (kinase activity)

Question 17

What does receptor tyrosine kinase ligand binding activate?

Answer 17

the intracellular tyrosine kinase domain

Question 18

What happens in a receptor tyrosine kinase when the intracellular tyrosine kinase domain is activated?

Answer 18

tyrosine is phosphorylated as well as tyrosine on other cytoplasmic proteins