Expression and characterization of the preoptic regulatory factor-1 and -2 peptides

The preoptic regulatory factors, PORF-1 and PORF-2, were originally detected as cDNAs from the rat preoptic area of the hypothalamus. Expression of the messenger RNAs is dependent on age, gender and hormonal status. PORF-1 is a putative transcription factor while PORF-2 affects cell growth. However, expression of peptides predicted from the PORF-1 and PORF-2 open reading frames has not been reported. The characterization of PORF-1 and PORF-2 peptides expressed in vitro and in vivo is described here. There are three potential PORF-1 peptides of 37, 59 and 86 amino acids, because of the presence of two TGA codons that can code either for termination or for selenocysteine incorporation in the PORF-1 open reading frame. All three peptides are detected after in vitro translation of full-length porf-1 brain mRNA. The two larger ones are found in normal male rat brain. The expression of a given peptide in bacteria depends upon the host strain. In contrast, a single 75 amino acid PORF-2 peptide is detected by in vitro translation, in transformed bacteria, and in rat brain. The PORF-1 and PORF-2 peptides have the charges and hydrophobicities predicted from their brain cDNA open reading frames. These small peptides may represent examples of multiple usage of single genetic loci in eukaryotes, giving rise to both a protein product and its regulatory peptide.