A luteinizing hormone receptor with a severely truncated cytoplasmic tail (LHR-ct628) desensitizes to the same degree as the full-length receptor.
The wild type murine luteinizing hormone (mLH) receptor, which in its mature form is predicted to be a protein of 674 amino acids (mLHR), and an artificially mutated form lacking the last 46 amino acids (mLHR-ct628) were stably expressed in murine L cells. Both forms stimulated adenylyl cyclase and underwent rapid desensitization. The mutation removed 1 tyrosine, 2 threonines, and 6 serines from the receptor. The results indicate that none of these potential phosphorylation sites participates in either adenylyl cyclase stimulation or receptor desensitization. Our results with the mLHR-ct628 (carboxyl-terminal amino acid sequence CCKHRAEL) differ from those reported recently for the essentially identically mutated rat LHR that lacks the last 43 amino acids (rLHR-ct631 with carboxyl-terminal amino acid composition CCKRRAELYRR). This 43-amino acid truncation was described to have the effect of preventing hormone-induced desensitization. While the reasons for the discrepant results are not known, our results do not support the proposal for a participatory role of the extreme carboxyl terminus of the receptor in its desensitization.
Zhu
X
X
Department of Cell Biology, Baylor College of Medicine, Houston, Texas 77030.
Gudermann
T
T
Birnbaumer
M
M
Birnbaumer
L
L
D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D015870:Gene Expression; D007739:L Cells / Q000378:metabolism; D007986:Luteinizing Hormone / Q000494:pharmacology; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010766:Phosphorylation; D016133:Polymerase Chain Reaction; D051381:Rats; D011974:Receptors, LH / Q000737:chemistry* / Q000235:genetics / Q000502:physiology*; D014162:Transfection
D006063:Chorionic Gonadotropin; D011974:Receptors, LH; D007986:Luteinizing Hormone; D000262:Adenylyl Cyclases