Fig. 7.

A LMP-1 interactions with both Jab1 and Smurf1 are required for full LMP-1 activity as observed in relative activities of recombinant LMP-1 proteins in potentiating BMP-induced reporter activity. The Jab-noninteracting LMP mutant (LMP1ΔJab1), like the Smurf-noninteracting LMP mutant (LMP-1ΔSmurf1), showed significant loss of BMP-2-potentiating activity as measured by relative luciferase activity. A double mutant (ΔΔ Smurf1–Jab1) lacking the required motifs for Smurf1 and Jab1 shows complete loss of BMP- potentiating activity. B Alkaline phosphatase assay confirms both Smurf1 and Jab1 interactions are required for full LMP-1 activity. While the ΔSmurf1 or ΔJab1 mutants of LMP-1 exhibited partial enhancement of BMP-induced ALP activity, the double mutant (ΔΔ Smurf1Jab1) exhibited little or no potentiating activity on BMP. This indicated that both Smurf1 and Jab1 interactions are necessary for LMP-1 to exhibit maximal BMP-2 potentiating activity. The data points were determined in triplicate