FIGURE 6:

Sgo1 can partially bypass the role of Mps1 in chromosome segregation and appears to act in the same pathway. (A) Overexpression of SGO1 allows cells to survive transient pharmacological inhibition of Mps1 kinase during mitosis. The cells were synchronized in S phase (at the restrictive temperature for the cdc34-2 allele), released into mitosis with or without the mps1-as inhibitor and with or without nocodazole, and then spotted on nonselective plates. (B) Localization of Sgo1-GFP to preanaphase spindles requires active Mps1. The images were taken 10 min after adding dimethyl sulfoxide (control samples) or the ATP analogue 1NM-PP1 to inhibit Mps1. (C) Overexpression of Sgo1-GFP on a 2-μm plasmid increases retention of Sgo1 on the mitotic spindle, even in the absence of targeting by Mps1. (D). Quantification of the fluorescence signal on the spindle for Sgo1-GFP, overexpressed Sgo1-GFP, Sli15-GFP, and Bub1-GFP in cells with active or inactive Mps1 kinase.