Chapter 5Ligand gated ion channels, intracellular

receptors and phosphorylation cascades

You Must Know

• The function of ligand gated ion channels, intracellular receptors and phosphorylation cascades.

ligand-gated ion channel

Ions

Plasma membrane

Signaling molecule(ligand)

1Gate

closed

Ligand-gated ion channel receptor

© 2014 Pearson Education, Inc.

Cellular response

Gateopen

2

Gate closed3

Steroid hormone interacting with an intracellular

receptor

DNA

Plasma membrane

Hormone- receptorcomplex

Receptorprotein

Newprotein

Hormone (testosterone)

mRNA

EXTRA-CELLULAR

FLUID

CYTOPLASM

NUCLEUS

© 2014 Pearson Education, Inc.

Hydrophobic

phosphorylation cascade

Receptor

Signaling molecule

Activated relay molecule

Inactiveprotein

kinase 1

Phosphorylation cascade

Inactiveprotein

kinase 2

Activeprotein

kinase 1

Activeprotein

kinase 2

Activeprotein

Inactiveprotein

Cellularresponse

ADP

ADP

© 2014 Pearson Education, Inc.

Protein phosphatases

Protein kinase

Figure 5.26

Phosphorylationcascade

Inactivetranscriptionfactor

NUCLEUS

CYTOPLASM

DNA

mRNA

Gene

Activetranscriptionfactor Response

Reception

Transduction

Growth factor

Receptor

© 2014 Pearson Education, Inc.