Chromosomal protein HMG-17. Complete human cDNA sequence and evidence for a multigene family.

Antibodies elicited against chromosomal protein HMG-17, purified from calf, were used to screen a human lambda gt11 cDNA expression library and isolate the full length cDNA coding for this protein. Sequence analysis reveals that the nucleotide distribution along this cDNA is highly asymmetric. The amino acid sequence, deduced from the reading frame, reveals that the human HMG-17 is, respectively, 96 and 92% homologous with the calf and chicken protein. The amino acid substitution are conservative suggesting evolutionary constraints on the conformation of the protein. The human genome contains 35-50 HMG-17 gene copies which, as revealed by Southern analysis, are distributed at several loci. Northern analysis of total RNA isolated from 3 human cell lines, indicates that each cell contains a single-size mRNA coding for this protein. Nucleotide sequences which cross-hybridize, under stringent conditions, with the human HMG-17 cDNA are present in the genome of rodents and absent from the genomes of sea urchin, Drosophila, and yeast. The availability of a probe for the HMG-17 gene may help elucidate the cellular role of this protein which may confer specific conformations to transcribable regions in the genome.