Structure of zebrafish MO25.

MO25, a conserved scaffold protein, activates the tumour suppressor LKB1 with the pseudokinase STRAD. MO25 also promotes the activities of the STE20-family kinases MST3, MST4, STK25, SPAK and OSR1. Zebrafish MO25 was purified and crystallized, and a crystal of zebrafish MO25 diffracted to 2.9 Å resolution and belonged to space group P3221, with unit-cell parameters a = b = 156.665, c = 221.251 Å. The structure of zebrafish MO25 was determined by molecular replacement. It is constituted of seven helical repeats. Structural comparison indicates that the overall structures of zebrafish and human MO25 are very similar, suggesting that MO25 has conserved functions in zebrafish. This work provides a structural basis for further functional and evolutionary studies of MO25.