A single serine residue at position 375 of VP16 is critical for complex assembly with Oct-1 and HCF and is a target of phosphorylation by casein kinase II.

We show that VP16 is phosphorylated by cellular kinases in vivo and in vitro and map the major sites of phosphorylation to be on serines towards the C-terminus, downstream of position 370 in both cases. Deletion of the acidic activation domain had no effect on phosphorylation, refining the sites to between position 370 and 411. Within VP16, the C-terminal boundary for complex formation with Oct-1 and HCF lies at position 388, and between 370 and 388 lies one serine, at position 375.

The regulation of human globin gene switching.

This paper describes the mechanism of regulation of the human beta-globin on the basis of a number of natural mutations and experiments in transgenic mice. From these data we conclude that this multigene locus is regulated at a number of different levels involving specific interactions between the Locus Control Region (LCR) and the individual genes. Most important is the action of stage specific transcription factors acting on sequences immediately flanking the genes.

Importance of globin gene order for correct developmental expression.

We have used transgenic mice to study the influence of position of the human globin genes relative to the locus control region (LCR) on their expression pattern during development. The LCR, which is located 5' of the globin gene cluster, is normally required for the activation of all the genes. When the human beta-globin gene is linked as a single gene to the LCR it is activated prematurely in the embryonic yolk sac.

Hypersensitive site 4 of the human beta globin locus control region.

The Locus Control Region (LCR) of the human beta globin gene domain is defined by four erythroid-specific DNasel hypersensitive sites (HSS) located upstream of this multigene cluster. The LCR confers copy number dependent high levels of erythroid specific expression to a linked transgene, independent of the site of integration. To assess the role of the individual hypersensitive sites of the LCR, we have localized HSS4 to a 280bp fragment that is functional both in murine erythroleukaemia (MEL) cells and in transgenic mice.