The hydrophobic amino acid residues in the membrane-proximal C tail of the G protein-coupled vasopressin V2 receptor are necessary for transport-competent receptor folding.
It is believed that the membrane-proximal C tail of the G protein-coupled receptors forms an additional alpha helix with amphipathic properties (helix 8). It was previously shown for the vasopressin V2 receptor (V2R) that a conserved dileucine motif (L(339), L(340)) in this putative helix 8 is necessary for endoplasmic reticulum (ER) to Golgi transfer of the receptor. Here, we demonstrate that the other hydrophobic residues forming the non-polar side of this helix (F(328), V(332) and L(336)) are also transport-relevant. In contrast, the multiple serine residues contributing to the more hydrophilic side (S(330), S(331), S(333), S(334), S(338)) do not influence receptor trafficking. In addition, we show unambiguously by the use of pharmacological chaperones that the hydrophobic residues of the putative helix 8 do not form a transport signal necessary for receptor sorting into ER to Golgi vesicles. Instead, they are necessary to establish a transport-competent folding state in the early secretory pathway.
Thielen
Anja
A
Forschungsinstitut für Molekulare Pharmakologie (FMP), Robert-Rössle-Str. 10, 13125 Berlin, Germany.
Oueslati
Morad
M
Hermosilla
Ricardo
R
Krause
Gerd
G
Oksche
Alexander
A
Rosenthal
Walter
W
Schülein
Ralf
R
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001127:Arginine Vasopressin / Q000378:metabolism; D001692:Biological Transport / Q000502:physiology; D002460:Cell Line; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D017510:Protein Folding; D021382:Protein Sorting Signals; D017433:Protein Structure, Secondary; D017483:Receptors, Vasopressin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*
D021382:Protein Sorting Signals; D017483:Receptors, Vasopressin; D011993:Recombinant Fusion Proteins; D001127:Arginine Vasopressin