Bgs4 and its β(1,3)glucan are required for correct and stable CAR positioning in the cell middle. (A–E) Bgs4 absence generates oblique (dotted line) nodes, CAR (A and C; Rlc1 and Cdc15), and septa (B and C; Bgs1, Bgs3, Psy1, and CW staining). (D) Ultrastructure of oblique (arrow) and misdirected septa. Cells were grown in MM+S+T for 8 h. (E) Percentage of oblique CAR and septa. Error bars indicate SD. (F) Bgs4 absence causes oblique CAR (arrow) in the cell middle that form oblique septa (dotted line). Arrow in dotted line, partial CAR sliding. (G) Bgs4 absence generates defective CAR positioning and sliding in the cell middle until septum synthesis initiation and anchorage to the cell wall. Oblique CAR sliding (arrow) to perpendicular position (left). Perpendicular CAR sliding (right). (H) The defect in Bgs4 function (shown in the cwg1-2 mutant) causes similar oblique CAR and septa (dotted line). Cells were grown as in Fig. 1 B (F and G) or in YES medium at 25°C and shifted to 37°C for 5–6 h (H) and visualized by time-lapse. Bars: (cells) 5 µm; (septum details) 1 µm.