Glucagon induces a rapid and sustained phosphorylation of the human glucagon receptor in Chinese hamster ovary cells.
The glucagon receptor is a member of the G protein-coupled receptor superfamily. Since several G protein-coupled receptors undergo phosphorylation in response to agonist, we investigated the phosphorylation of the glucagon receptor following the addition of glucagon to a Chinese hamster ovary cell line expressing the human glucagon receptor (CHO/hGR). Glucagon induced a rapid, time and concentration-dependent phosphorylation of its receptor on serine residues. Neither forskolin nor phorbol ester increased receptor phosphorylation, suggesting that cAMP-dependent protein kinase and protein kinase C do not catalyze this phosphorylation event. Furthermore, two mutant cell lines expressing glucagon receptors with successively truncated receptor cytoplasmic tails were tested. A strong correlation between the number of potential phosphorylation sites, receptor phosphorylation and receptor internalization was observed, suggesting that phosphorylation of the glucagon receptor in CHO/hGR cells is functionally linked to its internalization.
Heurich
R O
RO
Bayer Corporation, Pharmaceutical Division, West Haven, Connecticut 06516, USA.
Buggy
J J
JJ
Vandenberg
M T
MT
Rossomando
A J
AJ
D000595:Amino Acid Sequence; D000818:Animals; D000906:Antibodies; D016466:CHO Cells; D005576:Colforsin / Q000494:pharmacology; D006224:Cricetinae; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D005934:Glucagon / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry / Q000276:immunology; D010710:Phosphates / Q000378:metabolism; D010750:Phosphoproteins / Q000096:biosynthesis / Q000302:isolation & purification / Q000378:metabolism; D010766:Phosphorylation; D010768:Phosphoserine / Q000032:analysis; D011493:Protein Kinase C / Q000378:metabolism; D018027:Receptors, Glucagon / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000187:drug effects / Q000378:metabolism; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D014162:Transfection
D000906:Antibodies; D010446:Peptide Fragments; D010710:Phosphates; D010750:Phosphoproteins; D018027:Receptors, Glucagon; D011994:Recombinant Proteins; D010768:Phosphoserine; D005576:Colforsin; D005934:Glucagon; D017868:Cyclic AMP-Dependent Protein Kinases; D011493:Protein Kinase C; D013755:Tetradecanoylphorbol Acetate