Sequence and structure conservation in yolk proteins and their genes

Area of Science:

• Molecular Biology
• Genetics
• Developmental Biology

Background:

• The yp1 and yp2 genes in Drosophila are responsible for producing egg yolk proteins.
• Their expression is tightly regulated by hormones and occurs in a coordinated manner.

Purpose of the Study:

• To determine the complete nucleotide sequence of the yp2 gene and the intergenic region between yp1 and yp2.
• To identify common features in the yp1 and yp2 genes and their encoded proteins to understand their coordinated, hormone-dependent expression.

Main Methods:

• Complete nucleotide sequencing of the yp2 gene and the intergenic region.
• Mapping of mature messenger RNA onto the yp2 gene sequence.
• Comparative analysis of yp1 and yp2 gene sequences and protein structures.

Main Results:

• Identified conserved consensus sequences in flanking regions common to many eukaryotic genes.
• Discovered an unusual potential stem-loop structure with regulatory elements (TATA box, capping site, rRNA homology, start codon).
• Found a conserved 13-nucleotide sequence similar to a progesterone-receptor binding site consensus.
• yp1 and yp2 proteins show 53% sequence homology and nearly identical predicted secondary structures.

Conclusions:

• The identified stem-loop structure and conserved 13-nucleotide sequence may play a role in the coordinated, hormone-dependent gene expression.
• The conserved secondary structure of the yolk proteins is likely important for their oligomerization and other functions.