cDNAs encoding the baboon thrombin receptor indicate a primate transcription start site upstream of putative sites reported for the human gene

Two cDNAs encoding the thrombin receptor of baboon vascular smooth muscle c ells have 5'-untranslated regions that begin upstream of multiple putative transcription initiation sites reported for the closely related human recep tor gene. The extent of these baboon 5'-untranslated cDNA regions and their close similarity to the corresponding human sequences suggest that there i s only one transcription initiation site of the primate thrombin receptor g ene, which might be linked to a typical TATA-box previously identified in t he upstream region of the human gene. It is possible that all primates have a unique thrombin receptor gene transcription start site. Inferences drawn from the baboon system map be usefully extrapolated to the human, in view of the extensive similarities seen between the nucleotide sequences of babo on and human thrombin receptor gene sequences in the 5'-untranslated and co ding regions. The extents of the 5'-untranslated region of the baboon cDNAs argue that the "multiple" transcription start sites identified for the hum an gene are artifactual. The striking differences in the reported baboon an d human transcription start sites warrant further investigation in view of the significant role played by the thrombin receptor in numerous vascular a nd cellular growth responses. (C) 2000 Elsevier Science Ltd. All rights res erved.