MOLECULAR-CLONING AND IDENTIFICATION OF A RABBIT SAPHENOUS-VEIN 5-HT1D-BETA RECEPTOR GENE

The molecular identity of the serotonin (5-HT) receptor subtypes that mediate contraction in the rabbit isolated saphenous vein remains uncl ear. In order to identify a 5-HT1-like receptor subtype in this tissue , three sets of oligonucleotide primers were designed according to the human 5-HT1D beta receptor gene sequence for use in reverse transcrip tion-polymerase chain reaction (RT-PCR). Amplification of specific PCR -products was obtained with rabbit saphenous vein total RNA reverse-tr anscribed into single-stranded cDNA. The PCR-amplified products were u sed to screen a rabbit genomic library. Sequencing of PCR-products and of a library clone revealed an open reading frame of 1173 base pairs. The deduced amino acid sequence is 91 to 93 % homologous to the human 5-HT1D beta, rat 5-HT1B and mouse 5-HT1B receptor subtypes. A Thr-355 was found in trans-membrane domain VII as for the human 5-HT1D beta r eceptor. Transient expression of this rabbit saphenous vein gene in Co s-7 cells yielded the following receptor binding profile : 5-Carboxami dotryptamine > 5-HT > Methiothepin > Naratriptan greater than or equal to Zolmitriptan > MX-462 greater than or equal to Sumatriptan > (+)-8 -OH-DPAT > CP 93,129. This binding profile together with its amino aci d sequence indicate that this rabbit gene encodes a 5-ht(1D beta) rece ptor.