Asymmetric mitotic segregation of the yeast spindle pole body

• Published in: Cell Vol. 69; no. 3; pp. 505 - 515
• Main Authors: Vallen, Elizabeth A., Scherson, Talma Y., Roberts, Tom, van Zee, Karen, Rose, Mark D.
• Format: Journal Article
• Language: English
• Published: Cambridge, MA Elsevier Inc 01.05.1992; Cell Press
• Subjects: Biological and medical sciences; Cell Compartmentation; Cell Cycle; Fluorescent Antibody Technique; Fundamental and applied biological sciences. Psychology; Fungal Proteins - metabolism; Growth, nutrition, metabolism, transports, enzymes. Molecular biology; Microbiology; Microscopy, Electron; Mitosis; Mycology; Nuclear Proteins - metabolism; Recombinant Fusion Proteins - metabolism; Saccharomyces cerevisiae; Saccharomyces cerevisiae Proteins; Spindle Apparatus - metabolism; Spindle Apparatus - ultrastructure; Gene organization; Yeast; Structure activity relation; Segregation; Cell cycle
• ISSN: 0092-8674; 1097-4172
• DOI: 10.1016/0092-8674(92)90451-H

The yeast KAR1 gene is required for spindle pole body (SPB) duplication and nuclear fusion. We determine here that KAR1-β-galactosidase hybrid proteins localize to the outer face of the SPB. Remarkably, after SPB duplication, the hybrid protein was found associated with only one of the two SPBs, usually the one that enters the bud. Using an ndc1 mutant, which forms a defective SPB at the nonpermissive temperature, we found that the hybrid was exclusively associated with the “new” SPB. Two regions of KAR1 contribute to its localization; an internal 70 residue region was necessary and sufficient to localize hybrids to the SPB, and the hydrophobic carboxyl terminus localized proteins to the nuclear envelope. The localization domains correspond to two functional domains required for SPB duplication. We suggest that KAR1 is anchored to the nuclear envelope and interacts with at least one other SPB component during the cell cycle.