Delta, a Drosophila neurogenic gene, is transcriptionally complex and encodes a protein related to blood coagulation factors and epidermal growth factor of vertebrates

Abstract

Delta (D1) is required for normal segregation of the embryonic ectoderm into neural and epidermal cell lineages in Drosophila melanogaster. Loss-of-function mutations in D1 and other zygotic neurogenic loci lead to expansion of the neuroblast population at the expense of the dermoblast population within the ectoderm. Characterization of the transcriptional organization and maternal/embryonic expression within the chromosomal interval corresponding to D1 reveals that the locus encodes multiple transcripts: a minimum of two maternal transcripts, approximately 4.5 and 3.6 kb in length, and four zygotic transcripts, approximately 5.4 (two distinct species), 3.5, and 2.8 kb in length. These transcripts differ on the bases of differential splicing and differential polyadenylation site choice. The DNA sequence of a cDNA clone representing the predominant transcripts of the locus indicates that D1 encodes a transmembrane protein homologous to blood coagulation factors and epidermal growth factor. The relationship between coding sequences and transcript-specific exons within the locus suggests that D1 encodes multiple translational products.