Biochem: Module 5- Principles Of Hormone Action

Front 1

Bmax

Back 1

also = R(0)

the maximal number of receptors available--> because a set amount, receptors are saturable

Front 2

K(D)

Back 2

affinity of a hormone to a receptor--> measured in units of hormone concentration

lower K(D) = higher affinity
higher K(D) = lower affinity

Front 3

EC50

Back 3

the hormone concentration that gives 1/2 of the cellular response

generally EC50 < K(D)

Front 4

Scatchard plot

Back 4

X-intercept = Bmax

K(D) = -1/slope
-->the higher the absolute value of the slope, the higher the affinity of the hormone for the recptor

Front 5

Membrane-bound vs. Intracellular Receptors

Back 5

Membrane-bound = peptide and proteins

Intracellular = thyroid and steroid

Front 6

Gαs

Back 6

β-adrenergic amines, glucagon, parathyroid hormone, many others

--> stimulate adenylate cyclase

Front 7

Gαi

Back 7

Acetylcholine, α-adrenergic amines, many neurotransmitters

-->inhibits adenylate cyclase

Front 8

Gαt

Back 8

Photons

-->stimulates cGMP phosphodiesterase

Front 9

Gαq

Back 9

Acetylcholine, α-adrenergic amines, many neurotransmitters

-->increases IP3 and intracellular calcium

Front 10

Gα13

Back 10

Thrombin, orther agonists

-->stimulates Na+ and H+ exchange

Front 11

Gαq transduction pathway

Back 11

Gαq --> stimulates phospholipase C-β (PLC)

PLC --->cleaves PIP2 ---> produce IP3 and DAG

IP3 --> increase Ca2+ release from ER
DAG + Ca2+ --> stimulates PKC -->phosphorylates substrates to regulate growth and secretion