AtNSI mutants impaired in their interaction with NSP and with AtNSI can interact with At6.8 and AtENA. NSI, NSII107T, NSIK136E, and NSID194G, each fused to the GAD in pBI771, were coexpressed in yeast strain PJ69-4A with At6.8 or AtENA, each fused to the GBD in pBI880. Histidine prototophy (growth on SC-Trp-Leu-His with 5 mm 3-amino-1,2,4-triazole [3-AT]) in this classic yeast two-hybrid assay indicates an interaction.