Multiple human tyrosine hydroxylase enzymes, generated through alternative splicing, have different specific activities in Xenopus oocytes.

A single human tyrosine hydroxylase (HTH) gene has been shown previously to generate four species of mRNA by alternative splicing. The four different HTH mRNAs were independently synthesized in vitro, using the SP6 transcription system. Each of these mRNA species was able to direct the synthesis of an active form of TH following injection into Xenopus oocytes. Quantitation of synthesized HTH polypeptides allowed the determination of the relative specific activity of each individual HTH form. A significant difference in specific activity was found between each form, suggesting that alternative splicing may play a role in regulating HTH activity in vivo.