Disease relevance of Yp3

• The female sterility mutation mapped some distance away from the yp3 gene on the X chromosome and we were able to separate the YP3 defect from the female sterility by recombination, thus producing a fertile line of flies having no YP3 in the eggs [1].

High impact information on Yp3

• In situ hybridization to polytene chromosomes demonstrated, in fact, that the YP3 gene is approximately 1000 kb from the closely spaced YP1 and YP2 genes [2].
• We have isolated recombinant DNA clones that contain the genomic sequences coding for the three most abundant proteins in Drosophila eggs, the yolk proteins (YP1, YP2 and YP3) [2].
• The amnioserosa, yolk, midgut and fat body, which play major roles in lipid storage, metabolism and developmental timing, were identified as frequent sites of nuclear receptor activity [3].
• It was found that during epiboly of the zebrafish embryo, the movement of the outer epithelium (enveloping layer) over the yolk cell surface involves the constriction of marginal cells [4].
• It is found in yolk sacs and the outer cells of pre-implantation mouse embryos, where interactions with cubilin result in nutrient endocytosis, and it may be important during implantation [5].

Biological context of Yp3

• The nucleotide sequence of the gene coding for Drosophila melanogaster yolk protein 3 [6].
• This shows that YP3 is not essential for embryogenesis [1].
• We describe a system for P element transformation using the complete and unaltered yp3 gene rather than reporter genes and describe sequences conferring correct expression in the ovary and carcass [7].
• We report here an analysis of the yolk protein 3 (yp3) gene and its flanking sequences by means of P-element mediated germ-line transformation and demonstrate that a 747 bp promoter region is sufficient to direct sex-specific expression in the female fat body and both the temporal- and cell-type-specificity of expression during oogenesis [8].
• 20-Hydroxyecdysone, but not juvenile hormone, regulation of yolk protein gene expression can be mapped to cis-acting DNA sequences [9].

Anatomical context of Yp3

• In Drosophila three yolk polypeptides (YP1, YP2 and YP3) are synthesized at two sites in the adult female: in the fat body tissue, from which they are transported via the haemolymph to the ovary, and in the ovarian follicle cells which surround the developing oocytes [10].
• The three yolk proteins (YP1, YP2 and YP3) of Drosophila melanogaster are synthesised in the fat body and ovarian follicle cells and selectively accumulated in the developing oocytes to provide a nutrient source for embryogenesis [11].
• When gap junctions are inhibited or yolk receptors mutated, ZAM particles fail to sort out the follicle cells [12].

Physical interactions of Yp3

• The developmental profile of fully activated, ligand refractory receptor complexes closely correlated with that of yolk protein expression, suggesting an intimate involvement of the ecdysone receptor complex in both the induction and maintenance of high level expression of yolk protein genes [13].

Analytical, diagnostic and therapeutic context of Yp3

• Characterization, molecular cloning and sequencing of YP3s1, a fertile yolk protein 3 mutant in Drosophila [1].
• Densitometry of fluorographs and gels has been used to compare the amount of the smallest vitellogenin polypeptide, yolk protein 3, synthesised by each tissue [14].

References