Single copy gene for the chicken non-histone chromosomal protein HMG-17.

A chicken genomic library was screened with the human cDNA encoding the non-histone chromosomal protein HMG-17 and a 4565-base pair fragment containing the entire gene encoding this protein was isolated and characterized. Sequence analysis of the fragment revealed that from the start to end of transcription, the HMG-17 gene is 3293 base pairs long and is comprised of 6 exons ranging in size from 30 to 890 base pairs. Upstream of the putative cap site are both a CAAT box and a TATA box as well as several Sp1 binding sites. The gene has an extremely high content of G and C residues (75%) in a 1150-base pair fragment starting 500 base pairs from the putative cap site. This region satisfies the definition of an HpaII tiny fragment island. Southern analysis indicated that there is a single copy of this gene in chickens, whereas Northern analysis revealed that a single transcript is being synthesized from this gene. A comparison of the chicken and human cDNA and protein sequences and subsequent calculation of the evolutionary rates indicated that HMG-17 is a slowly evolving gene. The present article, which is the first study on the isolation and characterization of a complete gene coding for a high mobility group non-histone protein, indicates that the gene has features characteristic of housekeeping genes.