Mutation of the phosphorylatable residue Thr429 in Glu of the human VPAC1 led to a constitutively desensitized receptor.
The hVPAC1 receptor is rapidly phosphorylated and internalized by agonists but not re-expressed at the membrane after washing. Mutation of Ser/Thr residues in the C-terminus reduced phosphorylation but not internalization that was abolished only when all the phosphorylatable residues were mutated. Substitution of Thr429 by Glu mimicking a phosphothreonin led to a mutant with unchanged binding properties, decreased coupling to adenylate cyclase consisting in a reduced VIP potency, increased basal and VIP stimulated phosphorylation, preserved internalization followed by a rapid receptor re-expression. These are the expected characteristics of a constitutively desensitized receptor, putting forward the role of Thr429 phosphorylation in that process.
Langlet
Christelle
C
Laboratoire de Chimie Biologique et de la Nutrition, School of Medicine, Université Libre de Bruxelles, 808 Route de Lennik-CP611, B-1070 Bruxelles, Belgium.
Nachtergael
Ingrid
I
Robberecht
Patrick
P
Langer
Ingrid
I
D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D018698:Glutamic Acid / Q000737:chemistry*; D006801:Humans; D009154:Mutation; D010455:Peptides / Q000737:chemistry; D010766:Phosphorylation; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I / Q000737:chemistry*; D013912:Threonine / Q000737:chemistry*
D010455:Peptides; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D013912:Threonine; D018698:Glutamic Acid; D000262:Adenylyl Cyclases