An extracellular congenital nephrogenic diabetes insipidus mutation of the vasopressin receptor reduces cell surface expression, affinity for ligand, and coupling to the Gs/adenylyl cyclase system.
The mutation of the type-2 vasopressin receptor (V2R) apparently responsible for X-linked congenital nephrogenic diabetes insipidus (CNDI) in the Q3 family consists of a T to C transition in codon 113, causing the change of Arg-113 to Trp. Arg-113 is located in the putative first extracellular loop of the V2R next to a frequently conserved Cys thought to interact via a disulfide bridge with a Cys of the second extracellular loop. The present study explored whether this mutation may account for the CNDI phenotype. The mutation was excised from the genomic DNA of a Q3 patient and introduced into the V2R cDNA, which was then placed into an expression plasmid and transfected into COS cells for transient expression and murine L cells for stable expression. Studies with L cells expressing similar levels of wild type and Q3 receptors showed that the mutant receptor has a 20-fold reduced affinity for arginine vasopressin (AVP) and stimulates adenylyl cyclase with an EC50 that is increased by a factor of about 60-fold. The same shift in the EC50 for adenylyl cyclase stimulation was obtained when deamino[8-D-Arg]vasopressin was substituted for AVP. Studies with COS cells revealed that at equal levels of transfected DNA, the mutant receptor is expressed at lower levels (about 20%) than the wild type receptor, indicating that the mutation hinders the transport of the receptor to the cell membrane.(ABSTRACT TRUNCATED AT 250 WORDS)
Birnbaumer
M
M
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.
Gilbert
S
S
Rosenthal
W
W
D000262:Adenylyl Cyclases / Q000502:physiology*; D000595:Amino Acid Sequence; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism*; D001483:Base Sequence; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D002522:Chlorocebus aethiops; D003894:Deamino Arginine Vasopressin / Q000378:metabolism / Q000494:pharmacology; D018500:Diabetes Insipidus, Nephrogenic / Q000235:genetics*; D019204:GTP-Binding Proteins / Q000378:metabolism; D006801:Humans; D007739:L Cells; D051379:Mice; D008969:Molecular Sequence Data; D017354:Point Mutation; D011485:Protein Binding; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D017483:Receptors, Vasopressin / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D015398:Signal Transduction
D017483:Receptors, Vasopressin; D011993:Recombinant Fusion Proteins; D001127:Arginine Vasopressin; D019204:GTP-Binding Proteins; D000262:Adenylyl Cyclases; D003894:Deamino Arginine Vasopressin