Identification and cloning of a glycoprotein hormone receptor from sea lamprey, Petromyzon marinus.
A full-length transcript encoding a functional lamprey glycoprotein hormone receptor I (lGpH-R I, GenBank AY750688) was cloned from the testes of the sea lamprey, Petromyzon marinus, using the GpH-R protein fingerprint GLYCHORMONER from the PRINTS database. The present study is the first to identify a GpH-R transcript in an agnathan, which is one of the only two representatives of the oldest lineage of vertebrates. The 719-amino acid full-length cDNA encoding lGpH-R I is highly similar and is likely a homolog of the vertebrate GpH-Rs (including LH, FSH, and TSH receptors). The key motifs, sequence comparisons, and characteristics of the identified GpH-R reveal a mosaic of features common to all other classes of GpH-Rs in vertebrates. The lGpH-R I was shown to activate the cAMP signaling system using human chorionic gonadotropin in transiently transfected COS-7 cells. The highest expression of the receptor transcript was demonstrated in the testes using reverse transcriptase-PCR. Lower levels of the receptor transcript were also detected in brain, heart, intestine, kidney, liver, muscle, and thyroid. The high expression of lGpH-R I in the testis and the high similarity with gnathostome gonadotropin hormone receptors suggest that lGpH-R I functions as a receptor for lamprey gonadotropin hormones. We hypothesize from these data that there is lower specificity of gonadotropin and its receptor in agnathans and that during co-evolution of the ligand and its receptor in gnathostomes, there were increased specificities of interactions between each GpH (TSH, LH, and FSH) and its receptor.
Freamat
Mihael
M
Department of Biochemistry and Molecular Biology, University of New Hampshire, Room 310, 46 College Road, Durham, NH 03824, USA.
Kawauchi
Hiroshi
H
Nozaki
Masumi
M
Sower
Stacia A
SA
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D019556:COS Cells; D002522:Chlorocebus aethiops; D000242:Cyclic AMP / Q000378:metabolism; D019143:Evolution, Molecular; D006801:Humans; D008969:Molecular Sequence Data; D048428:Petromyzon / Q000378:metabolism*; D010802:Phylogeny; D018000:Receptors, Peptide / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction / Q000502:physiology; D014018:Tissue Distribution
D018000:Receptors, Peptide; D000242:Cyclic AMP