Disease relevance of Yp1

• The sterility and YP1 quantity phenotypes were not genetically separated from each other or from the structural gene for YP1, indicating that the mutation is located in or near Yp1 [1].
• Mutant yolk proteins lead to female sterility in Drosophila [2].

High impact information on Yp1

• The yolk protein 1 gene (yp1) of Drosophila melanogaster is expressed only in the ovarian follicle cells and the fat bodies of adult females [3].
• A tissue-specific transcription enhancer from the Drosophila yolk protein 1 gene [3].
• Thus a small regulatory region acts in vivo as a positive enhancer to determine the fat body expression pattern of yp1 [3].
• These experiments raise the question of the functional role of the proximity of Yp1 and Yp2 and provide a mechanism for a search for mutations altering the hormonally regulated function of these three genes [4].
• 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 [5].

Biological context of Yp1

• In addition to extensive homology between the protein coding regions, we found two small regions of homology between yp3 flanking sequences and a segment of DNA required for normal expression of the yolk protein 1 gene in adult female fat bodies [6].
• We have successively deleted intergenic DNA upstream of the YPI or the YPII transcription start site and have assayed the dependence of transcription efficiency an template concentration [7].
• Transcription was studied in vitro from templates carrying YPI or YPII promoter regions separately [7].
• The transcription start sites of YPI and YPII genes are linked by 1225 base pairs of intergenic DNA and the genes are transcribed in divergent directions [7].
• We propose that the mutant protein is secreted into the subbasement membrane space, but because of the amino acid substitution in YP1, the oligomers containing YP1 condense into SBMM, which cannot penetrate the basement membrane [8].

Anatomical context of Yp1

• 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 [9].
• Transcripts from the introduced Yp1 were not found in male flies but appeared on a normal developmental schedule in adult females, accumulating in their body walls and ovarian follicles but not in guts or malpighian tubules [10].
• Immunogold studies demonstrate that newly synthesized YPs in the normal and mutant strains share secretory vesicles with putative, vitelline membrane proteins and that the translocation of follicle cell YP is not through the membrane along the interfollicular spaces but directly through the plasmalemma facing the oocyte [2].
• The globules are also incapable of passing into the hemolymph but they are morphologically distinct from those of fs(1)1163 [2].
• YP-containing aggregates, ultrastructurally similar to those in the fat body of each respective mutant, were found in the space between the plasmalemma and the vitelline membrane and embedded within the membrane itself [2].

Associations of Yp1 with chemical compounds

• Transformed male flies do not exhibit ADH activity when injected with 20-hydroxyecdysone while synthesis of native yolk proteins is induced [11].
• One component of the system is the tetracycline-controlled transactivator gene under the control of the fat body and female-specific transcription enhancer from the yolk protein 1 gene [12].
• Estradiol induced a vitellogenin gene transcript of 6500 nucleotides at 6 h and reached a maximum at 72 h after stimulation [13].
• It is suggested that transcription of the YP genes is under the cell-autonomous control of the sex genes and that the sex genes do not exert their effect by modulating the levels of steroid hormones in adults [14].

Other interactions of Yp1

• In contrast to YPI it resembles no significant homology to the 3' end of 18S rRNA [15].
• Probes representing two multigene families (beta-tubulin and yolk-protein) hybridized as would be expected if all sites had been conserved in the two species on the same chromosomal elements [16].
• Our results demonstrate that mago nashi encodes a maternal transcript detected in both blastomeres and yolk cell at the 1-2 cell stages, and in the blastoderm during segmentation [17].
• This motif is homologous to the phorbol 12-tetradecanoate 13-acetate- and cAMP-responsive elements of eukaryotic genes and the regulatory proximal sequence elements of the U1 small nuclear RNA gene and is also present in the promoter of the Drosophila melanogaster yolk protein factor 1 gene [18].
• A YP1 promoter that contains the tissue-, temporal-, and sex-specific controlling elements for expression was fused to the reporter gene, alcohol dehydrogenase (Adh) [19].

Analytical, diagnostic and therapeutic context of Yp1

• Densitometry of fluorographs and gels has been used to compare the amount of the smallest vitellogenin polypeptide, yolk protein 3, synthesised by each tissue [20].
• 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 [21].
• An electrophoretic mobility shift assay was used to study VG1 binding to labeled HA 8-, 10-, 20-, 30-, and 40-mers, and although no stable VG1 binding was observed to labeled 8-mers, the equilibrium dissociation constant (100 nM) for VG1 with HA(10) was estimated from densitometry analysis of the free oligosaccharide [22].

References