抄録
We recently reported that the high intracellular stability of the N-terminus-deleted human tyrosine hydroxylase (TH) type 1 mutants might be generated by the loss of a PEST (proline, glutamate/aspartate, serine and threonine) motif located in the N-terminus sequence of Met1-Lys12. However, it is not clear whether only the PEST motif can affect the intracellular stability of human TH type 1 (hTH1) proteins. This study was performed to confirm a role of the PEST motif on the stability of hTH1. Wild-type hTH1 and the 6 mutants (del-12, del-22, del-32 and del-42, in which the first 12, 22, 32 and 42 amino acid residues deleted, respectively; del-Pro2, the Pro2 residue deleted; del-Ala11, the Ala11 residue deleted) were expressed in AtT-20 mouse neuroendocrine cells in order to clarify how deeply the PEST motif is involved in the intracellular stability of hTH1 protein. The western blot analyses revealed that the mutants del-22, del-32, del-42 and del-Ala11 were much more stable than wild-type in the cells. These results indicate that the PEST motif is critical in regulating the intracellular stability of hTH1 protein. Moreover, it has been reported that the phosphorylations of TH at serine residues, Ser19, Ser31 and/or Ser40 induce the change in the tertiary structure of the N-terminus of TH protein. Therefore, in this report, we also suggest that the PEST motif and the phosphorylations can affect the intracellular stability of hTH1 protein, synergistically. [J Physiol Sci. 2007;57 Suppl:S143]
