A transcriptionally active human type II gonadotropin-releasing hormone receptor gene homolog overlaps two genes in the antisense orientation on chromosome 1q.12.
GnRH-II peptide hormone exhibits complete sequence conservation across vertebrate species, including man. Type-II GnRH receptor genes have been characterized recently in nonhuman primates, but the human receptor gene homolog contains a frameshift, a premature stop codon (UGA), and a 3' overlap of the RBM8A gene on chromosome 1q.12. A retrotransposed pseudogene, RBM8B, retains partial receptor sequence. In this study, bioinformatics show that the human receptor gene promoter overlaps the peroxisomal protein 11-beta gene promoter and the premature UGA is positionally conserved in chimpanzee. A CGA [arginine (Arg)] occurs in porcine DNA, but UGA is shifted one codon to the 5' direction in bovine DNA, suggesting independent evolution of premature stop codons. In contrast to marmoset tissue RNA, exon- and strand-specific probes are required to distinguish differently spliced human receptor gene transcripts in cell lines (HP75, IMR-32). RBM8B is not transcribed. Sequencing of cDNAs for spliced receptor mRNAs showed no evidence for alteration of the premature UGA by RNA editing, but alternative splicing circumvents the frameshift to encode a two-membrane-domain protein before this UGA. A stem-loop motif resembling a selenocysteine insertion sequence and a potential alternative translation initiation site might enable expression of further proteins involved in interactions within the GnRH system.
Morgan
Kevin
K
Medical Research Council Human Reproductive Sciences Unit, University of Edinburgh Academic Centre, Edinburgh EH16 4SB, United Kingdom. k.morgan@hrsu.mrc.ac.uk
Conklin
Darrell
D
Pawson
Adam J
AJ
Sellar
Robin
R
Ott
Thomas R
TR
Millar
Robert P
RP
D000236:Adenoma; D017398:Alternative Splicing / Q000235:genetics; D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D001943:Breast Neoplasms; D002144:Callithrix; D002822:Choriocarcinoma; D002878:Chromosomes, Human, Pair 1; D016373:DNA, Antisense; D016889:Endometrial Neoplasms; D019143:Evolution, Molecular; D005260:Female; D006801:Humans; D019169:Jurkat Cells; D008297:Male; D008969:Molecular Sequence Data; D009447:Neuroblastoma; D009690:Nucleic Acid Conformation; D016366:Open Reading Frames / Q000235:genetics; D010802:Phylogeny; D010911:Pituitary Neoplasms; D011401:Promoter Regions, Genetic / Q000235:genetics; D011471:Prostatic Neoplasms; D011966:Receptors, LHRH / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017279:Selenocysteine / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D015533:Transcriptional Activation / Q000235:genetics*
D016373:DNA, Antisense; C427484:GNRHR2 protein, human; D011966:Receptors, LHRH; D017279:Selenocysteine