Phys Exam 3 (secondary messengers)

What is the adenylate cyclase/CAMP mechanisim?

Hormone binds to receptor → G-proteins → on adenylate cyclase → converts ATP → turns on cAMP → turns on protein kinase (phosphorylates enzymes)

How do you turn off the adenylate cyclase / cAMP mechanism?

G-proteins turn themselves off

PDE destroys cAMP

Protein phosphatase dephosphorylates

What polar hormones use the cAMP system?

monoamines (NE and E), Beta adrenergic, and polypeptides/glycoproteins

Describe the phospholipase c mechanism

Hormone binds to receptor → g-protein→ turns on phospholipase c → pulls apart membrane phospholipid to make IP3 and DAG → IP3 opens CA channels on ER -> CA binds to calmodulin in the cytoplasm → ca/calmodulin complex turns on protein kinase

How do you turn off the phospholipase c mechanism?

G proteins turn themselves off

Protein phosphatase

Ca pump’s move ca back into ER

IP3 phosphatase → breaks down IP3

What hormones use the phospholipase system?

alpha adrenergic

What are the ligands for tyrosine kinase mechanism usually?

growth factors

What is the tyrosine kinase receptor composed of?

2 inactive monomers

1 outside = ligand binding domain

1 inside = catalytic/enzymatic domain

Describe the tyrosine kinase mechanism

2 molecules of growth factor bind to ligand-binding domain → dimerize → autophosphorylation → changes conformation of catalytic domain → turns on enzyme → catalytic domains phosphorylate tyrosine signal proteins → signal proteins activate metabolic pathway

how do you turn off tyrosine kinase mechanism?

protein tyrosine phosphatase