HUMAN SUPT5H PROTEIN, A PUTATIVE MODULATOR OF CHROMATIN STRUCTURE, ISREVERSIBLY PHOSPHORYLATED IN MITOSIS

The Saccharomyces cerevisiae proteins Spt4p, Spt5p and Spt6p are invol ved in transcriptional repression by modulating the structure of chrom atin. From HeLa cells we have purified a human homologue of Spt5p, Sup t5hp, and show here that the protein is reversibly phosphorylated in m itosis, The cloned cDNA predicts a protein of 1087 residues with 31% i dentity to yeast Spt5p. It includes an acidic N-terminus, a putative n uclear localization signal and a C-terminal region containing two diff erent repeated motifs, One of them, with the consensus sequence P-T/S- P-S-P-Q/A-S/G-Y, is similar to the C-terminal domain in the largest su bunit of RNA polymerase II. (C) 1997 Federation of European Biochemica l Societies.