Phosphorylation of the third intracellular loop of the mouse alpha1b-adrenergic receptor by cAMP-dependent protein kinase.
The third intracellular loop of adrenergic receptors has been implicated in their interaction with guanine nucleotide-binding proteins (G proteins). One of the mechanisms involved in the modulation of receptor function is the phosphorylation of specific residues by intracellular kinases. alpha1b-Adrenergic receptor is phosphorylated in vitro by cAMP-dependent protein kinase (PKA), although its physiological effect remains to be determined. We have produced fusion proteins formed by glutathione S-transferase and sequences of the third intracellular loop of mouse alpha1a-, alpha1b-, and alpha1d-adrenergic receptor subtypes, and used them as substrates for PKA. Only the fusion protein containing the alpha1b sequence was phosphorylated in vitro by this kinase. Site-directed mutagenesis of a serine (homologue to serine 278 of the rat sequence, RSS) to an alanine residue precluded phosphorylation by PKA.
Alonso-Llamazares
A
A
Departamento de Bioquímica y Biología Molecular, Universidad de León, Spain.
Casanova
E
E
Zamanillo
D
D
Ovalle
S
S
Calvo
P
P
Chinchetru
M A
MA
D000595:Amino Acid Sequence; D000818:Animals; D001921:Brain / Q000187:drug effects / Q000378:metabolism; D000242:Cyclic AMP / Q000494:pharmacology*; D051379:Mice; D008969:Molecular Sequence Data; D010766:Phosphorylation; D011494:Protein Kinases / Q000494:pharmacology*; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects* / Q000378:metabolism*
D018340:Receptors, Adrenergic, alpha-1; D000242:Cyclic AMP; D011494:Protein Kinases