YP, fs(1)K313, vitellogenin, fs(1)M35, yolk protein
Gene model reviewed during 5.49
442 (aa); 49.6 (kD predicted)
Tyrosine sulfation occurs in the female only and plays an essential functional role.
Click to get a list of regulatory features (enhancers, TFBS, etc.) and gene disruptions (point mutations, indels, etc.) within or overlapping Dmel\Yp2 using the Feature Mapper tool.
GBrowse - Visual display of RNA-Seq signalsView Dmel\Yp2 in GBrowse 2
Please Note This section lists cDNAs and ESTs that fall within the genomic extent of the gene model, which may include cDNAs and ESTs of genes within introns, or of overlapping genes. Please see GBrowse for alignment of the cDNAs and ESTs to the gene model.
For each fully sequenced cDNA the DGRC maintains various forms of the cDNA (e.g tagged or untagged) in several different host vectors for subsequent cloning and expression in Drosophila and Drosophila cell lines.
The p47 polypeptide seen previously in ACF (ATP-utilizing chromatin assembly and remodeling factor) fractions (FBrf0095281) has been found to be identical to Yp2 and appears to have been a contaminant in these earlier ACF fractions.
20-Hydroxyecdysone, but not juvenile hormone, regulation of yolk protein gene expression can be mapped to cis-acting DNA sequences. It is not clear whether regulation by 20-hydroxyecdysone is direct or indirect. Methoprene up-regulation is only observed when native yolk protein genes are assayed, suggesting that it may operate through influencing stability of the message.
By comparing methylation by Ecol\dam methylase between euchromatic and heterochromatic genes it was determined that the heterochromatic state does not prevent methylase accessibility in vivo.
srp is expressed in the ovaries of adult flies where it produces an ovary specific protein isoform. The srp protein binds to a 12bp ovarian follicle cell-specific regulatory element located between the divergently transcribed Yp1 and Yp2. The 12bp element activates both in vivo and in vitro transcription of Yp1 and Yp2.
Insertion of the gypsy\su(Hw)BR into the Yp1 Yp2 intergenic region does not alter temporal or tissue-specific expression of the Adh or Ecol\lacZ reporter genes but does repress the Yp1 Yp2 fat body enhancer elements.
The yolk protein genes Yp1 and Yp2 are only expressed in the ovary and fat body of females if they are supplied with proteinaceous food. Several regulatory regions have been shown to independently confer nutritional regulation on the expression of Yp1 and Yp2.
343bp of immediately upstream Yp2 sequences are sufficient for expression in the fat bodies.
Pattern of osmium zinc iodide staining in the cortical cytoplasm varies in relation to the number of yolk protein structural genes.
Newly synthesised yolk proteins in normal and mutant strains share secretory vesicles with putative vitelline membrane proteins. Translocation of follicle cell yolk protein is not through the membrane along the interfollicular spaces, but directly through plasmalemma facing the oocyte.
Evolutionary conservation of specificity of yolk protein uptake by the oocyte is studied throughout Diptera.
Female flies with varying numbers of Yp1, Yp2 and Yp3 genes have been generated. Each yolk protein gene makes an equivalent contribution to the fecundity and fertility of the female, and they do not individually provide unique functions to the embryo. The number of eggs laid by a female depends on the number of genes encoding yolk proteins present in the genome, and the probability of an egg producing an adult depends on the number of yolk protein genes present in the mother.
The male and female products of dsx when expressed in E.coli bind specifically to the fat body enhancer (FBE) of Yp1 and Yp2. This demonstrates a direct interaction between the sex determination hierarchy and a target gene.
Yp1 and Yp2 are transcribed in the same sub-populations of ovarian follicle cells. This expression is directed by two enhancers: ovarian enhancer 1, located in the 1226bp intergenic region, and ovarian enhancer 2 located within the first exon of Yp2.
Two cis-acting regions influence the transcription of both Yp1 and Yp2 in the ovaries. One is located in the 1224bp intergenic region and determines the stage and cell type specificity of ovarian transcription. The other is in the first intron of Yp2 and acts across the Yp2 promoter region to stimulate Yp1 transcription in ovaries.
Yolk proteins share a certain homologous domains with human low-density lipoproteins and human lipoprotein lipase.
The sex-, time- and tissue-specific expression of the Yp1 and Yp2 genes, divergently transcribed and separated by 1225bp, indicates that there are two tissue-specifying elements acting on each gene. One is necessary for expression in fat body and the other for expression in the ovary.
Hormonal and genetic regulation of yolk formation has been reviewed.
Structural gene for the yolk protein YP2 found in recently-emerged female flies. Protein migrates at different rates in SDS-polyacrylamide gels when encoded by the electrophoretic variants Yp2F (fast) and Yp2S (slow), alleles that are female fertile and produce normal amounts of YP2. A mutant Yp2M (=Yp212-1245) is female fertile but lays fewer eggs than normal (Mohler, Postlethwait and Shirk) and does not contain yolk protein in the hemolymph or ovaries.
Postlethwait, Jan. 1979.