Function and regulation of the ubiquitin ligase TRAC-1 in T cells. (360G-Wellcome-078170_Z_05_Z)

The ubiquitin ligase TRAC-1 was identified in a screen for modulators of T cell activation and may, given its selective expression in haematopoietic cells, be a key regulator of lymphocyte function. So far, we have found that TRAC-1 inhibits expression of CD69, an early activation marker. Using a variety of functional, biochemical and cell biological experiments, we propose to evaluate the precise role of TRAC-1 in T cells. The key goals are: To characterise the regulatory role of TRAC-1 interactions with membranes and Cbl proteins that were identified in our preliminary experiments. Association with membranes depends on myristoylation, a novel modification for ubiquitin ligases that may regulate access to substrates. Binding to Cbl appears to potentiate TRAC-1 activity. To identify TRAC-1 substrates. This will be approached by two complementary methods: a BacterioMatch two-hybrid screen will be employed to identify TRAC-1-interacting proteins; biochemical analysis will be used to establish specific T cell activation events that are affected by TRAC-1. To analyse TRAC-1 expression in different T cell subsets, which will reveal whether TRAC-1 activity is restricted to specific differentiation or activation states. This study will contribute to two important research areas, those of T cell regulation and ubiquitination.