# A new hybrid post-translational modification—have you lost your (MARUb)les?

## TL;DR

Scientists discovered a new protein modification called MARUbylation, combining ubiquitin and ADP-ribose, which may be important for immune responses.

## Contribution

The discovery of MARUbylation, a hybrid post-translational modification involving ubiquitin and mono-ADP-ribose.

## Key findings

- MARUbylation occurs naturally in cells when interferon is present.
- The modification involves a poly-ubiquitin chain linked via mono-ADP-ribose to target proteins.
- It may play a role in interferon signaling, a key part of the innate immune system.

## Abstract

Recent work in The EMBO Journal describes a new hybrid post-translational modification of proteins, composed of a poly-ubiquitin chain that is attached to a target protein via a mono-ADP-ribose (MAR) moiety. This “MARUbylation” is likely to play important functions during interferon signalling, a core component of innate immunity.

New work finds ubiquitination of protein-linked mono-ADP-ribose to occur endogenously in cells upon interferon stimulation.