Initially viewed as a simple “degradation tag”, ubiquitin (Ub) is now recognised as a sophisticated post-translational platform with diverse roles in protein fates. Ubiquitination can impact protein transcription, translation, trafficking and turnover. For plasma membrane proteins, Ub can alter expression at the cell surface with important functional consequences. In immune cells, plasma membrane proteins are highly important. They function to transmit signals from inflammatory stimuli, detect pathogens, present material from invading pathogens or tumours, guide cell migration and stimulate, or inhibit, immune functions in other cells. Therefore, ubiquitination and regulation of immune cell surface proteins is critical for immunity. Little analysis of ubiquitination has been undertaken in primary immune cells that offer insight into specialised pathways of fundamental biology. CI Mintern leads one of the few laboratories worldwide studying ubiquitination in primary immune cells. With recent corresponding author manuscripts in Science and Nature Communications CI Mintern has made landmark discoveries of ubiquitination in adaptive immunity. She has described its role in promoting unprecedented forms of immune cell communication, development, and its contribution to vaccination. She has used proteomics to identify new substrates of membrane protein ubiquitination in primary immune cells and using CRISPR/Cas9 screening has identified ubiquitin like protein 3 (UBL3) as a new participant in ubiquitination in mouse and human immune cells.