The zyxin-related protein TRIP6 interacts with PDZ motifs in the adaptor protein RIL and the protein tyrosine phosphatase PTP-BL

The small adaptor protein RIL consists of two segments, the C-terminal LIM and the N-terminal PDZ domain, which mediate multiple protein-protein inter actions. The RIL LIM domain can interact with PDZ domains in the protein ty rosine phosphatase PTP-BL and with the PDZ domain of RIL itself, Here, we d escribe and characterise the interaction of the RIL PDZ domain with the zyx in-related protein TRIP6, a protein containing three C-terminal LIM domains . The second LIM domain in TRIP6 is sufficient for a strong interaction wit h RIL, A weaker interaction with the third LIM domain in TRIP6, including t he proper C-terminus, is also evident. TRIP6 also interacts with the second out of five PDZ motifs in PTP-BL, For this interaction to occur both the t hird LIM domain and the proper C-terminus are necessary. RNA expression ana lysis revealed overlapping patterns of expression for TRIP6, RIL and PTP-BL , most notably in tissues of epithelial origin. Furthermore, in transfected epithelial cells TRIP6 can be co-precipitated with RIL and PTP-BL PDZ poly peptides, and a co-localisation of TRIP6 and RIL with F-actin structures is evident. Taken together, PTP-BL, RIL and TRIP6 may function as components of multi-protein complexes at actin-based sub-cellular structures.