Human Physiology Cell Signaling Receptors

1st step in Steroid/Thyroid Signal Transduction Pathway

Steroid/thyroid hormone diffuses through the plasma membrane and binds to the receptor that is located in the nucleus or cytosol

2nd step in Steroid/Thyroid Signal Transduction Pathway

Creates receptor hormone complex that binds to specific region of DNA

3rd step in the Steroid/Thyroid Hormone Signal Transduction Pathway

Changes gene expression and triggers the transcription of a specific gene

4th step in the Steroid/Thyroid Hormone Signal Transduction Pathway

New protein is created by mRNA leaving the nucleus and being translated by ribosomes

5th step in the Steroid/Thyroid Hormone Signal Transduction Pathway

This new protein alters cellular response

1st Step in Nitric Oxide Signal Transduction Pathway

Nitric oxide diffuses through membrane and binds to receptor within the cell

2nd Step in Nitric Oxide Signal Transduction Pathway

Enzyme guanylyl cyclase is activated by the bind of NO to the receptor. This causes GTP to be converted into cyclic GMP

3rd Step in Nitric Oxide Signal Transduction Pathway

cGMP binds to and activates protein kinase G

4th step in Nitric Oxide Signal Transduction Pathway

Protein kinase G phosphorylates effector protein

1st step in Ion Channels

Chemical messenger binds to receptor on the outer surface of the plasma membrane

2nd Step in Ion Channels

The channel opens in response to the binding of the chemical messenger

3rd Step in Ion Channels

Specific ions can diffuse through open ion channel

4th Step in Ion Channels

Influx or efflux of ions creates a cellular response

1st step in Tyrosine Kinase Receptor

A water-soluble messenger binds to the receptor Tyrosine Kinase on the outer surface of the plasma membrane

2nd step in Tyrosine Kinase Receptor

Tyrosine kinase dimerizes with nearby messenger bound receptor tyrosine kinase

3rd step in Tyrosine Kinase Receptor

The tyrosine kinase portion of the receptor is activated by dimerization. The dimers cross phosphorylate each other.

4th Step in Tyrosine Kinase Receptor

phosphorylated sites on receptor serve as docking sites for relay proteins

5th step in Tyrosine Kinase Receptor

Relay proteins bind to docking sites; tyrosine kinase portion of receptor phosphorylates and activates relay proteins.

6th Step in Tyrosine Kinase Receptor

Once activated the relay proteins trigger intracellular pathway that synthesizes/activates effector protein

7th Step in Tyrosine Kinase Receptor

Activated/synthesized effector protein alters cellular response

1st Step in Gyanylyl Cyclase Receptor

Water soluble messenger binds to guanylyl cyclase receptor on the outer surface of the plasma membrane

2nd Step in Guanylyl Cyclase Receptor

The Guanylyl Cyclase with bound water soluble messenger dimerizes with another messenger bound receptor

3rd Step in Guanylyl Cyclase Receptor

Dimerization causes the activation of the receptor which causes GTP to be converted to cyclic GMP

4th Step in Guanylyl Cyclase Receptor

cGMP binds to protein kinase G (PKG) and activates it

5th Step in Guanylyl Cyclase Receptor

ONce activated PKG phosphorylates effector protein which activates or inhibits effector protein

6th Step in Guanylyl Cyclase Receptor

Phosphorylated protein alters cellular response

1st Step in Enzyme-coupled receptors

Water-soluble messenger binds to JAK-coupled receptor that is on outer surface of plasma membrane

2nd Step in Enzyme-Coupled Receptors

A JAK-coupled receptor that has messenger bound to it dimierizies with a nearby messenger-bound JAK coupled receptor

3rd Step in Enzyme-Coupled Receptors

Dimerization leads to the receptors being pulled closer so each JAK can cross phosphorylate tyrosine kinase amino acid on the other one. The JAKs phosphorylates tyrosine a.a on cytosolic portion

4th Step in Enzyme-Coupled Receptors

The phosphorylated sites on dimers act as docking sites for STAT relay proteins

5th Step in Enzyme-Coupled Receptors

When docked, JAKS phosphorylate the STATS

6th Step in Enzyme-Coupled Receptors

The phosphorylated STATs leave docking sites, enter nucleus, and bind to DNA which trigers the transcription of a particular gene

7th Step in Enzyme-Coupled Receptors

New protein is synthesized which alters the cellular response

1st Step in G-Protein Coupled Receptor

When alpha subunit is bound to GDP, G protein is inactive

2nd step in G Protein Receptor

G-protein coupled receptor activates when a messenger binds to it; causes conformational change in receptor alpha subunit which releases GDP in exchange for GTP; Binding of GTP activates G proteins

3rd Step in G Protein Receptor

The alpha subunit dissociates from the beta gamma complex; the alpha subunit or beta gamma complex moves along the cytosolic surface of the plasma membrane to a target protein

4th Step in G Protein Receptor

The alpha subunit has GTPase activity that hydrolyzes GTP to GDP and a phosphate group GDP remains bound to the alpha subunit, the phosphate group is released

5th step in G Protein Receptor

GDP on the alpha subunit causes the alpha subunit to recombine with the beta gamma complex, inactivating the G protein

1st Step in G Protein Coupled Receptor: cAMP

Water soluble messenger binds to a G protein coupled receptor on the outer surface of plasma membrane

2nd Step in G Protein Coupled Receptor: cAMP

Messenger-receptor complex activates G protein Gs

3rd Step in G Protein Coupled Receptor: cAMP

Activated Gs protein stimulates membrane bound adenylyl cyclase

4th Step in G Protein Coupled Receptor: cAMP

Adenylyl cyclase converts ATP into second messenger cAMP

5th Step in G Protein Coupled Receptor: cAMP

cAMP binds to and activates protein kinase A (PKA). PKA phosphorylates protein

6th Step in G Protein Coupled Receptor: cAMP

Activated PKA phosphorylates effector protein; phosphorylation either activates or inhibits protein

7th Step in G Protein Coupled Receptor: cAMP

Phosphorylated Effector Protein alters cellular response

1st Step in G protein coupled receptor: IP3, DAG, Ca2+

Water-soluble messenger binds to G-protein coupled receptor on outer surface of plasma membrane

2nd Step in G protein coupled receptor: IP3, DAG, Ca2+

Messenger-receptor complex activates G protein called Gq

3rd Step in G protein coupled receptor: IP3, DAG, Ca2+

Gq protein activates membrane-bound enzyme phospholipase C

4th Step in G protein coupled receptor: IP3, DAG, Ca2+

Phospholipase C cleaves membrane phospholipid to form second messengers inositol triphosphate (IP3) and diaglycerol (DAG)

5th Step in G protein coupled receptor: IP3, DAG, Ca2+

IP3 travels to endoplasmic reticulum and binds to and opens IP3-gated channels

6th Step in G protein coupled receptor: IP3, DAG, Ca2+

Ca2+ diffuses through open IP3-gated channels to cytosol

7th Step in G protein coupled receptor: IP3, DAG, Ca2+

DAG and Ca2+ bind to and activate protein kinase C (PKC)

8th Step in G protein coupled receptor: IP3, DAG, Ca2+

Activated PKC phosphorylates effector protein; either activating or inhibiting the protein

9th Step in G protein coupled receptor: IP3, DAG, Ca2+

Phosphorylated effector protein alters cellular response