The Bbp1p-Mps2p complex connects the SPB to the nuclear envelope and is essential for SPB duplication.
In budding yeast, microtubules are organized by the spindle pole body (SPB), which is embedded in the nuclear envelope via its central plaque structure. Here, we describe the identification of BBP1 in a suppressor screen with a conditional lethal allele of SPC29. Bbp1p was detected at the central plaque periphery of the SPB and bbp1-1 cells were found to be defective in SPB duplication. bbp1-1 cells extend their satellite into a duplication plaque like wild-type cells; however, this duplication plaque then fails to insert properly into the nuclear envelope and does not assemble a functional inner plaque. This function in SPB duplication is probably fulfilled by a stable complex of Bbp1p and Mps2p, a nuclear envelope protein that is also essential for duplication plaque insertion. In addition, we found that Bbp1p interacts with Spc29p and the half-bridge component Kar1p. These interactions are likely to play a role in connecting the SPB with the nuclear envelope and the central plaque with the half-bridge.
Schramm
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C
The Beatson Institute for Cancer Research, CRC Beatson Laboratories, Glasgow G61 1BD, UK.
Elliott
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S
Shevchenko
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A
Schiebel
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E
D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism*; D007150:Immunohistochemistry; D008565:Membrane Proteins / Q000378:metabolism*; D008854:Microscopy, Electron; D008868:Microtubule Proteins; D008938:Mitosis / Q000235:genetics; D008954:Models, Biological; D009685:Nuclear Envelope / Q000378:metabolism; D009687:Nuclear Proteins / Q000378:metabolism*; D011485:Protein Binding; D029701:Saccharomyces cerevisiae Proteins; D008941:Spindle Apparatus / Q000235:genetics / Q000378:metabolism*; D013489:Suppression, Genetic; D015003:Yeasts / Q000235:genetics / Q000378:metabolism
C404863:BBP1 protein, S cerevisiae; D005656:Fungal Proteins; C074559:KAR1 protein, S cerevisiae; C120755:MPS2 protein, S cerevisiae; D008565:Membrane Proteins; D008868:Microtubule Proteins; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins