FIGURE 1.

MTF-1 can be sumoylated. CHO K1 cells were transfected with His₆-tagged MTF-1 and/or FLAG-tagged SUMO-1 plasmid (A). In addition to MTF-1 and SUMO-1 plasmids, SENP1 or SENP2 plasmids were also co-transfected (B). Cellular MTF-1 was immunoprecipitated with anti-His₆ antibodies (A) or pulled down with Co²⁺-charged metal-affinity beads (B) for Western blot analysis. Proteins were visualized with the designated antibodies. Solid and empty arrows indicate the position of the sumoylated and nonsumoylated MTF-1, respectively. C, mouse MTF-1 primary sequence was analyzed with a computer program and two potential sumoylation sites were predicted. D, the potential sumoylation sites (K14 and K627) on MTF-1 were substituted with arginine singly or in combination (K14R, K627R, and K14R/K627R), then proteins were expressed in the cells. Cell extracts were immunoprecipitated (IP) for Western blotting analysis for sumoylation site identification. E, sequence comparison of potential sumoylation sites on MTF-1 among various species. Arrow indicates the potential sumoylation site. Asterisks indicate the potential region of SIM.