Figure 3: kip1Δ cells are defective in the slow phase of anaphase B and prolong anaphase. kip1Δ cells (yeast strain AFS404) were recorded as described in Fig. 1. (A) Distance between spindle pole bodies versus time. (B) Distance between centromeres versus time. The time of sister chromatid separation is indicated by t = 0.

Mentions: During anaphase, kip1Δ cells exhibited a normal rapid elongation phase (0.51 μm/min; Fig. 3 A; Table II) in contrast to cin8Δ cells, whose spindles elongate slowly. However, during the slow phase of spindle elongation in anaphase B, the spindles of kip1Δ cells (0.12 μm/min) elongated more slowly than wild-type spindles (0.2 μm/min; Fig. 3 A; Table II). This suggests that Kip1p and Cin8p have distinct roles in anaphase B: Cin8p is required for rapid elongation at the beginning of mitosis and Kip1p is more important during the slower phase of spindle elongation.

Straight AF, Sedat JW, Murray AW - J. Cell Biol. (1998)

Bottom Line: Genetic analysis in budding yeast has identified two sets of kinesin-like motors, Cin8p and Kip1p, and Kar3p and Kip3p, that have overlapping functions in mitosis.Despite their functional overlap, each motor mutant has a specific defect in mitosis: cin8Delta mutants lack the rapid phase of anaphase B, kip1Delta mutants show defects in the slow phase of anaphase B, and kip3Delta mutants prolong the duration of anaphase to the point at which the spindle becomes longer than the cell.The kip3Delta and kip1Delta mutants affect the duration of anaphase, but cin8Delta does not.

Affiliation: Department of Physiology, School of Medicine, University of California San Francisco, San Francisco, California 94143, USA. aaron_straight@hms.harvard.edu

Abstract: The mitotic spindle is a complex and dynamic structure. Genetic analysis in budding yeast has identified two sets of kinesin-like motors, Cin8p and Kip1p, and Kar3p and Kip3p, that have overlapping functions in mitosis. We have studied the role of three of these motors by video microscopy of motor mutants whose microtubules and centromeres were marked with green fluorescent protein. Despite their functional overlap, each motor mutant has a specific defect in mitosis: cin8Delta mutants lack the rapid phase of anaphase B, kip1Delta mutants show defects in the slow phase of anaphase B, and kip3Delta mutants prolong the duration of anaphase to the point at which the spindle becomes longer than the cell. The kip3Delta and kip1Delta mutants affect the duration of anaphase, but cin8Delta does not.