The C terminal tail of the histamine H2 receptor contains positive and negative signals important for signal transduction and receptor down-regulation.
To examine the role of the C terminal tail in H2 receptor regulation, three cDNAs, encoding truncated histamine H2 receptor mutants (H2T295, H2T307, and H2T341), were constructed and stably transfected in Chinese hamster ovary (CHO) cells. The amino acids before position 307 appear to be necessary for proper receptor transport or folding, as no detectable H2 receptor binding of the H2T295 was observed after transfection. Truncation of the C terminal tail by 51 amino acids (H2T307) did not affect the binding properties of H2 antagonists and histamine or histamine-induced signaling. Yet, removal of 17 amino acids generated a mutant receptor (H2T341), which was able to form a ternary complex but was unable to fully activate the Gs protein on histamine exposure. Agonist-induced but not the cyclic AMP-dependent H2 receptor down-regulation was more profound for the H2T307 receptor, indicating that different structural elements of the H2 receptor protein are involved in the cyclic AMP-dependent and independent pathways of H2 receptor down-regulation. Taken together, in this study we identified regions in the C terminal tail of the H2 receptor that act as positive and/or negative signals in H2 receptor signaling and down-regulation.
Smit
M J
MJ
Leiden/Amsterdam Center for Drug Research, Department of Pharmacochemistry, Vrije Universiteit, The Netherlands.
Timmerman
H
H
Blauw
J
J
Beukers
M W
MW
Roovers
E
E
Jacobs
E H
EH
Hoffmann
M
M
Leurs
R
R
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D016466:CHO Cells; D002462:Cell Membrane / Q000378:metabolism; D006224:Cricetinae; D000242:Cyclic AMP / Q000378:metabolism; D017931:DNA Primers; D015536:Down-Regulation; D006146:Guanidines / Q000378:metabolism; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000494:pharmacology; D006632:Histamine / Q000378:metabolism / Q000494:pharmacology*; D006635:Histamine H2 Antagonists / Q000378:metabolism; D007457:Iodine Radioisotopes; D007700:Kinetics; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D017433:Protein Structure, Secondary; D051381:Rats; D011970:Receptors, Histamine H2 / Q000096:biosynthesis / Q000737:chemistry* / Q000502:physiology; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
D017931:DNA Primers; D006146:Guanidines; D006635:Histamine H2 Antagonists; D007457:Iodine Radioisotopes; D011970:Receptors, Histamine H2; D011994:Recombinant Proteins; C063279:iodoaminopotentidine; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006632:Histamine; D000242:Cyclic AMP