# Purification tags markedly affect self‐aggregation of CPEB3

## TL;DR

This study shows that purification tags can significantly influence how a protein called CPEB3 aggregates, which is important for understanding protein behavior in diseases and biological functions.

## Contribution

The study reveals that His₆-GFP and His₁₂ tags affect the aggregation of CPEB3's intrinsically disordered region.

## Key findings

- His₆-GFP and His₁₂ tags alter liquid droplet formation in CPEB3's IDR.
- Uncleaved tags also impact amyloid fibril formation in CPEB3 fragments.
- Tag effects must be considered to accurately interpret protein aggregation assays.

## Abstract

Since protein aggregation—including liquid–liquid phase separation (LLPS) and amyloid fibril formation—plays a critical role in both diseases and biological functions, understanding the mechanisms underlying protein aggregation is essential. Recombinant proteins are commonly used in vitro to investigate protein aggregation processes. However, if the purification tags remain uncleaved, they may affect the results and hinder accurate interpretation. Our findings demonstrate that the His6‐GFP and His12 tags significantly affect liquid droplet and amyloid fibril formation in the intrinsically disordered region (IDR) of mouse cytoplasmic polyadenylation element‐binding protein 3 (CPEB3) and its fragments. This study shows that the purification tags significantly affect aggregation assays, making it essential to account for their influence to accurately interpret protein aggregation.

Although recombinant proteins are used to study protein aggregation in vitro, uncleaved tags can interfere with accurate interpretation. Our findings demonstrate that His₆‐GFP and His₁₂ tags significantly affect liquid droplet and amyloid fibril formation in the intrinsically disordered region (IDR) of mouse cytoplasmic polyadenylation element‐binding protein 3 (CPEB3) and its fragments. Our results indicate that tag effects must be considered for accurate interpretation of protein aggregation.