# TurboID-mediated proximity labeling technologies to identify virus co-receptors

## TL;DR

This paper introduces a new method using TurboID to find virus co-receptors, successfully identifying AXL as a co-receptor for SARS-CoV-2.

## Contribution

The novel use of TurboID-mediated proximity labeling to identify virus co-receptors, specifically AXL for SARS-CoV-2.

## Key findings

- AXL is a co-receptor that facilitates SARS-CoV-2 entry into host cells.
- TurboID-mediated proximity labeling effectively identifies proteins interacting with ACE2 on the cell membrane.
- The method can be applied to discover other virus co-receptors.

## Abstract

Virus receptors determine the tissue tropism of viruses and have a certain relationship with the clinical outcomes caused by viral infection, which is of great importance for the identification of virus receptors to understand the infection mechanism of viruses and to develop entry inhibitor. Proximity labeling (PL) is a new technique for studying protein-protein interactions, but it has not yet been applied to the identification of virus receptors or co-receptors. Here, we attempt to identify co-receptor of SARS-CoV-2 by employing TurboID-catalyzed PL. The membrane protein angiotensin-converting enzyme 2 (ACE2) was employed as a bait and conjugated to TurboID, and a A549 cell line with stable expression of ACE2-TurboID was constructed. SARS-CoV-2 pseudovirus were incubated with ACE2-TurboID stably expressed cell lines in the presence of biotin and ATP, which could initiate the catalytic activity of TurboID and tag adjacent endogenous proteins with biotin. Subsequently, the biotinylated proteins were harvested and identified by mass spectrometry. We identified a membrane protein, AXL, that has been functionally shown to mediate SARS-CoV-2 entry into host cells. Our data suggest that PL could be used to identify co-receptors for virus entry.