# Molecular evidence supports the functionality of a protein-trapped endogenous allele of Dally-like protein

## TL;DR

This study confirms that a modified version of the Dally-like protein in fruit flies is functional and essential for development.

## Contribution

The study provides molecular evidence that the SVS-tagged Dlp protein is functional without producing a wild-type isoform.

## Key findings

- SVS-dlp flies do not produce a wild-type Dlp isoform.
- The SVS-tagged Dlp is functional and supports embryonic development.
- Alternative splicing does not rescue the wild-type Dlp in SVS-dlp flies.

## Abstract

The
Drosophila
glypican Dally-like protein (Dlp) is an evolutionarily-conserved cell-surface protein that modulates extracellular distribution of several secreted ligands for cell signaling. Several fly lines expressing tagged
dlp
have been used to study the role of Dlp
in vivo
including the

PBac{602.P.SVS-1}dlp
[CPTI000445]

protein-trap line, which encodes StrepII-Venus-StrepII (SVS)-tagged Dlp from the endogenous locus.
dlp
is essential for embryonic development, and the
SVS-dlp
line is homozygous viable. Although this suggests that the SVS-tagged Dlp is functional, it is possible that that the
SVS-dlp
flies produce wild-type
dlp
isoform through alternative splicing, contributing to their survival. Here, we used a molecular analysis approach to show that the
SVS-dlp
flies do not produce wild-type isoform, confirming that the SVS-tagged Dlp is indeed functional.