A baffling protein

Barrier-to-autointegration factor (BAF) is a cellular protein that prevents destructive insertions of retroviruses into their own genomes. In the August 1 Proceedings of the National Academy of Sciences, Zheng et al. propose that BAF's usual function may be in chromosome condensation (Proc. Natl. Acad. Sci. USA 2000, 97:8997-9002). BAF added to DNA forms primarily a dodecamer that binds five or six DNA molecules. The processes of DNA binding and formation of the higher-order BAF multimer are coupled. Interference with BAF function by RNAi in worm embryos results in abnormal chromosome segregation, with chromatin trailing between segregating chromosomes. Thus BAF may function in chromosome organization or condensation.