The regulatory domain of a larval serum protein gene in Drosophila melanogaster.

DNAse I hypersensitive sites have been shown to be present at the 5' end of each of the larval serum protein genes (LSPs) when they are expressed in the fat body. They are absent from the same inactive genes in embryos. A 4.4-kb genomic fragment containing the coding region for LSP 1 alpha and 1.5 kb of 5'-flanking sequence has been reintroduced into the germ line of a strain containing an electrophoretic variant form of the alpha gene. The expression of the reintegrated gene is normal with respect to the amount of protein produced and the temporal and spatial distribution of the transcript. A comparison has been made of the chromatin configuration of the reintroduced and endogenous alpha genes and the same pattern of DNase I hypersensitivity is found. The hypersensitive regions have been located on the 5' sequence of the LSP 1 alpha gene and their sequences compared with known hypersensitive regions of other genes.