High impact information on STU2

• Instead, the checkpoint deficiency leads to deregulation of microtubule-associated proteins Cin8 and Stu2, which, in the absence of both chromosome cohesion and bipolar attachment of kinetochores to microtubules, induce untimely spindle elongation, causing premature chromosome separation [1].
• Our data suggest that Stu2p regulates microtubule dynamics through two separate activities [2].
• A recent study in budding yeast indicates that when a chromosome is transported to the minus end of a spindle microtubule, its kinetochore-bound microtubule plus end-tracking protein (+TIP) Stu2 may move to the plus end to promote rescue; i.e., to switch the depolymerizing end to a polymerizing end [3].
• Thus, the SPB-associated Spc72-Stu2 complex plays a key role in regulating microtubule properties [4].
• We further show that the activity of Stu2 is opposed by the activity of the kinesin-related protein Kip3 [5].

Biological context of STU2

• STU2 is an essential gene and encodes a protein whose sequence is similar to proteins identified in a variety of organisms [6].
• Interestingly, among these candidates, we identified two genes, SSO1 and STU2, involved in protein transport and spindle pole body formation, respectively, suggesting puzzling connections with the translation termination process [7].
• Two-hybrid analysis suggests that this phosphorylation may attenuate the interaction between Kar9p and the XMAP215-homologue Stu2p [8].
• Stu2 promotes mitotic spindle elongation in anaphase [5].
• Control of microtubule dynamics by Stu2p is essential for spindle orientation and metaphase chromosome alignment in yeast [9].

Associations of STU2 with chemical compounds

• We propose that phosphorylation at serine 197 regulates the release of Kar9p from Stu2p at the SPB, either to clear it from the mother-SPB or to allow it to travel to the plus end [8].

Physical interactions of STU2

• The yeast spindle pole body component Spc72p interacts with Stu2p and is required for proper microtubule assembly [10].

Other interactions of STU2

• 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 [11].
• Thus, Stu2, Bik1, and Bim1 interact physically but do not appear to be arranged in a single unique complex [11].
• Using live cell imaging and mutations affecting microtubule binding proteins and kinetochore function, we identify a regulatory mechanism for spindle microtubule dynamics involving Stu2p and the core kinetochore component, Ndc10p [12].

References