Disease relevance of BIM1

• Deletion of BIM1 results in a strong bilateral karyogamy defect, hypersensitivity to benomyl, and aberrant spindle behavior, all phenotypes associated with mutations affecting microtubules in yeast, and inviability at extreme temperatures (i.e., >/=37 degrees C or </=14 degrees C) [1].
• Bim1 homolog EB1 was originally identified through its interaction with adenomatous polyposis coli (APC) tumor suppressor, raising the possibility that an APC-EB1 linkage orients microtubules in higher cells [2].

High impact information on BIM1

• Here, we show that Kar9 directs microtubule orientation by acting through Bim1, a conserved microtubule-binding protein [2].
• We examined the regulation of the proapoptotic activity of the BH3-only protein Bim [3].
• During G1, microtubules in cells lacking BIM1 showed reduced dynamicity due to a slower shrinkage rate, fewer rescues and catastrophes, and more time spent in an attenuated/paused state [4].
• Here we investigate the physical and functional interactions among three +TIPs in S. cerevisiae, Stu2, Bik1, and Bim1 [5].
• Here, we show that deletion of four C-terminal residues of the budding yeast gamma-tubulin Tub4 (tub4-Deltadsyl) perturbs Bim1 and Kar9 localization to SPBs and Kar9-dependant spindle positioning [6].

Biological context of BIM1

• Both of these stt1 phenotypes were suppressed by the over-expression of BIM1 [7].

Anatomical context of BIM1

• However, deletion of BIM1 eliminated Kar9p localization along cytoplasmic microtubules [8].
• Paradoxically, +TIPs such as the EB1 orthologue Bim1 and Kar9 also associate with spindle pole bodies (SPBs), the centrosome equivalent in budding yeast [6].

Physical interactions of BIM1

• These experiments demonstrate that the interaction of cytoplasmic microtubules with the Kar9p cortical attachment site requires the microtubule-binding protein Bim1p [8].

Other interactions of BIM1

• PKC1, a protein kinase C homologue of Saccharomyces cerevisiae, participates in microtubule function through the yeast EB1 homologue, BIM1 [7].
• These assays additionally implicated three proteins, Bim1, Ump1, and YKL171W, in proteasome function [9].
• Two-hybrid, coimmunoprecipitation, and in vitro binding assays demonstrate that they associate in all pairwise combinations, although the interaction between Stu2 and Bim1 may be indirect [5].

References