PROMOTER SEQUENCE AND EXPRESSION OF THE LEUCINE-RICH REPEAT GENE LRR47 - EVIDENCE FOR CYTOPLASMIC AND NUCLEAR-LOCALIZATION IN DROSOPHILA EMBRYOS AND CELLS

In Drosophila, proteins containing leucine-rich repeats (LRR) play div erse roles during embryonic development. In particular, they function in cell adhesion and cellular signalling and have in common the abilit y to mediate reversible protein-protein interactions. The sequence and chromosomal location of Drosophila LRR47, which encodes a protein wit h eight LRR repeats, were reported previously. In this paper the 5' fl anking region of the LRR47 gene is described and the initiation point for the maternal transcription unit is defined. LRR47 belongs to a sub family of LRR proteins that have in common the ability to interact wit h ras GTPase. Whole-mount in situ hybridization studies show that the LRR47 transcript is uniformly distributed in early cleavage embryos bu t becomes depleted at the termini by the blastoderm stage. There is a specific requirement for ras function in the embryonic termini at this developmental stage. The distribution of LRR47 protein in embryos and tissue culture cells was also studied. The protein is present in both the cytoplasm and nuclei of embryos until gastrulation and is seen to persist in the nuclei of the amnioserosa until later stages of develo pment. The protein is also constitutively present in growing SL2 cultu re cells and again is present in both cytoplasm and nuclei. These resu lts suggest that LRR47 function may be modulated in the cell or nuclea r division cycle. (C) 1998 Elsevier Science B.V. All rights reserved.