Mutations in the beta-propeller domain of the Drosophila brain tumor (brat) protein induce neoplasm in the larval brain.

Inactivation of both alleles of the fruit fly D. melanogaster brain tumor (brat) gene results in the production of a tumor-like neoplasm in the larval brain, and lethality in the larval third instar and pupal stages. We cloned the brat gene from a transposon-tagged allele and identified its gene product.

Rop and Ras2, members of the Sec1 and Ras families, are localized in the outer membranes of labyrinthine channels and vesicles of Drosophila nephrocyte, the Garland cell.

The product of the ras opposite (rop) gene is an essential component of secretion processes in Drosophila. The rop gene product is homologous to the Caenorhabditis elegans UNC-18 and the rat munc-18/n-Sec1/rbSec1 proteins, implicated in the final steps of neurotransmitter exocytosis in nerve terminals, and the bovine mSec1 protein implicated in the secretion of catecholamines in chromaffin cells. The mammalian brain protein has been shown to exert its activity in the presynaptic membrane through transient interaction with syntaxin, an integral component of this membrane.

The Drosophila Ras2 and Rop gene pair: a dual homology with a yeast Ras-like gene and a suppressor of its loss-of-function phenotype.

The promoter of the Drosophila melanogaster Ras2 gene is bidirectional, regulating an additional gene oriented in the opposite polarity. The two divergently transcribed genes are only 93 bases apart and deletion analysis proved that common cis-acting elements within this promoter region are required for the transcriptional activity of both genes. We cloned the gene paired with Ras2 in the bidirectional promoter and isolated cDNAs corresponding to its mRNA.

Maternal and embryonic transcripts of Drosophila proto-oncogenes are expressed in Schneider 2 culture cells but not in l(2)gl transformed neuroblasts.

The transcription patterns of Drosophila melanogaster src, abl and two ras homologs were analyzed in normal Drosophila tissue, in neuroblasts derived from tumorous larval brain of the mutant lethal(2)giant larvae [l(2)gl] and in Schneider 2 tissue culture cells. Our results show that, in addition to constitutive transcripts, the src, abl, ras1 and ras3 genes express a set of maternal/embryonic-specific transcripts. By using these transcripts as differentiation markers we show that, in spite of their embryonic-like, undifferentiated phenotype, the l(2)gl transformed neuroblasts are authentic larval cells.

Developmental changes in expression of the Drosophila melanogaster epidermal growth factor receptor gene.

A Drosophila gene homologous to the human EGF receptor gene has recently been isolated and sequenced. Two transcripts, 7.6- and 7.