Map position and nucleotide sequence of the gene for the large structural phosphoprotein of human cytomegalovirus

Human cytomegalovirus particles contain a phosphoprotein of 150,000 (pp150) apparent molecular weight in their matrix; the protein appears particularly reactive in Western blot analyses with human antisera. The gene for pp150 was mapped by screening a bacteriophage lambda gt11 cDNA expression library with monospecific rabbit antisera. Subsequent hybridization of cDNA with cosmid and plasmid clones containing the human cytomegalovirus strain AD169 genome mapped the gene to HindIII fragments J and N. The gene is transcribed into a late 6.2-kilobase RNA. The nucleotide sequence of this region was determined, and a transcription initiation site and two polyadenylation sites of an abundant transcript were located by primer extension and nuclease protection experiments. The reading frame for pp150, deduced from computer analyses, gives rise to a polypeptide of 1,048 amino acids in length; protein secondary structure analysis revealed multiple beta-pleated sheets in hydrophilic clusters, providing a possible explanation for the immunogenic properties of the polypeptide.