Identification and characterization of TRH-precursor peptides.

We have now characterized five cryptic peptides in rat brain together with two partially processed TRH-progenitor sequences. Our studies indicate that pro-TRH is processed at paired basic residues to a family of peptides, including TRH, and flanking and intervening sequences. These cryptic sequences may have evolutionary significance or have functions during mRNA processing, translation, and posttranslational processing, or may be biologically active peptides in their own right. We have recently identified a TRH producing-cell line and are characterizing cell lines stably transfected with expression vectors containing prepro-TRH cDNA. These models should provide further insights into the posttranslational processing of pro-TRH.