Characterization of temperature-sensitive alleles of the septation initiation network protein Mob1 in Schizosaccharomyces pombe.

Schizosaccharomyces pombe Mob1 is the regulatory subunit of the protein kinase Sid2 . The Sid2- Mob1 complex is the most downstream acting component of the septation initiation network (SIN). In the absence of functional Mob1 , cells fail cytokinesis and become multinucleate. Here we characterize a set of temperature-sensitive mob1 alleles by identifying the mutations within each allele, characterizing the extent of their growth defects, and visualizing the cell defects. Based on structural modeling, we hypothesize that the Mob1 mutations interfere with Mob1 stability and its ability to bind the N-terminal regulatory region of Sid2 .