Alternative splicing at the 3'-cDNA of human tryptophan hydroxylase.

Two alternatively spliced transcripts of human tryptophan hydroxylase (TPH) were identified that differed at the 3' end of the open reading frame. Comparison of the human TPH cDNA and genomic sequences revealed that an intron containing an in-frame stop codon could be alternatively spliced out of intron 11. This splicing would give rise to two human TPH isoforms with different C termini; the one that derives from the nonspliced intron contains a putative cyclic AMP-dependent protein kinase site, whereas the other one, which is 22 amino acids longer, does not. Analysis of various human tissues by RT-PCR revealed that the spliced TPH mRNA species was detected in all the postmortem tissues we tested, but the nonspliced species was expressed in only some tissues.