Figure 8.

TOG5 is essential for proper mitotic spindle formation. (A) Representative immunofluorescence images of the four mitotic phenotypes categorized in S2 cell mitotic spindle rescue experiments: bipolar/monastral bipolar, misaligned, monopolar, and multipolar. Bar, 5 µm. (B) Quantification of mitotic phenotypes for Msps depletion and rescue experiments. Depleting Msps decreases the number of bipolar/monastral bipolar mitotic spindles compared with control cells, with a concomitant increase in aberrant spindle phenotypes including misaligned and monopolar. Transfection of FL Msps or Δ34₂ rescues mitotic spindle defects. Deleting TOG5 or mutating TOG5-MT binding residues results in a dramatic decrease in the ability of these constructs to rescue bipolar/monastral bipolar mitotic spindle formation. The percentage of misaligned and monopolar mitotic spindles increases for mutation constructs containing F1204E (HR A^FE) and lateral tubulin-binding mutations (Lateral^{ME, RE, KE}), respectively. Number of mitotic cells analyzed and number of independent experiments are shown in parentheses. Mean ± SEM are shown.