A HUMAN SEROTONIN-7 RECEPTOR PSEUDOGENE

Although the serotonin-7 receptor was cloned several years ago, its lo calization in brain tissues remains confusing because of the existence of a related expressed pseudogene, the sequence of which has not hith erto been reported. During the course of searching for related recepto r genes, we also searched for this pseudogene to determine its sequenc e. Human genomic DNA was screened for dopamine and serotonin receptor- like genes, using the polymerase chain reaction method and degenerate oligonucleotide primers based on the similar sequences in the transmem brane-6 and -7 regions of the serotonin-5A, the serotonin-7, and the d opamine D2, D3 and D4 receptors. This resulted in one of the clones ha ving a 115 bp fragment, of which 89% of the bases were identical to th e transmembrane-6 and -7 regions of the serotonin-7 receptor sequence. The fragment was radiolabelled and used to screen a human fetal brain cDNA library. A. novel cDNA clone of 1326 bp was isolated. Based on t he nucleotide sequence, 88% of the bases in this sequence of the pseud ogene are identical to the human serotonin-7 receptor coding sequence. However, compared to the serotonin-7 receptor DNA sequence, the pseud ogene sequence has nucleotide deletions and insertions, resulting in f rame-shifts and stop codons. It was concluded that this sequence repre sented a pseudogene related to the serotonin-7 receptor gene. (C) 1998 Elsevier Science B.V.