The order of priority of some common functional groups in amino acids is

TLS Online TPP Program

#Id: 9072

#XL - T Zoology

In resting state 

basal level of PDE activity keeps cAMP levels below those necessary for PKA activation.

TLS Online TPP Program

#Id: 9073

#XL - T Zoology

TLS Online TPP Program

#Id: 9074

#XL - T Zoology

Activation of β-adrenergic receptors causes activation of C subunits of PKA which phosphorylate PDE, stimulating its catalytic activity.

TLS Online TPP Program

#Id: 9075

#XL - T Zoology

Active PDE hydrolyzes cAMP, driving cAMP levels back to basal levels.

TLS Online TPP Program

#Id: 9076

#XL - T Zoology

A G protein– coupled receptor kinase phosphorylates serine and threonine residues in the

cytoplasmic segments of activated GPCRs

TLS Online TPP Program

#Id: 9077

#XL - T Zoology

β-Arrestin (Arr) binds to these phosphorylated receptors. Clathrin and AP2, two other proteins bound by β-arrestin, promote endocytosis of the receptor.