Nucleotide sequence of pho-4+, encoding a phosphate-repressible phosphate permease of Neurospora crassa

Abstract

The nucleotide (nt) sequence of the Neurospora crassa pho-4+ gene, which encodes a phosphate-repressible phosphate permease, has been determined. The gene specifies a protein of 590 amino acids (aa) and contains two introns. Two RNA transcripts of 3.3 and 2.4 kb have been identified, and transcription start points (tsp) and termination sites and/or processing sites have been located. The 3.3-kb message is initiated about 890 nt upstream from the tsp for the 2.4-kb transcript. A hydropathy profile of the aa sequence suggests ten to twelve membrane-spanning helices with a large hydrophilic domain between the eighth and ninth helices. This model for the predicted secondary structure of the protein is very similar to models proposed for other sequenced integral membrane proteins from both prokaryotes and eukaryotes. Since very few permease-encoding genes of eukaryotes have been examined in molecular detail, it will be of interest to compare the sequence of pho-4+ with those encoding other anion transport proteins, as they become available.