Sequence and structural organization of murine cytomegalovirus immediate-early gene 1

In murine cytomegalovirus, abundant immediate-early transcription
originates from 0.769 to 0.815 map units of the genome. This region
contains the immediate-early gene (gene ieI) which encodes pp89, a
phosphoprotein active in transcriptional regulation. In this paper
we report on the precise location, structural organization, and
sequence of gene ieI. The predominant ieI transcript, a
2.75-kilobase mRNA, is generated by splicing and composed of four
exons. The precise termini of the 2.75-kilobase mRNA and the
positions of the exons were determined by nuclease digestion
experiments with either 5' or 3' end-labeled DNA fragments or in
vitro transcribed cRNA probes. Exons of 300, 111, 191, and 1,703
nucleotides are separated by introns of 825, 95, and 122
nucleotides. The first AUG is located in the second exon of 111
nucleotides, and a single open reading frame of 1,785 nucleotides
predicts a protein of 595 amino acids with a calculated molecular
weight of 66,713. The N-terminal region of the protein contains
sequences similar to a consensus sequence of histone 2B proteins.
The regulatory function of pp89 and the role of this protein as an
immunodominant antigen are discussed in relation to the amino acid
sequence.