High impact information on MOB1

• We investigated the function of two S. cerevisiae proteins related to the MEN proteins Mob1p and Dbf2p kinase [1].
• The simultaneous binding of Cdc14p and Mob1p to the SPB in early anaphase suggests that Cdc14p initially activates the MEN [2].
• We propose that Mob1 promotes this activation process by enabling Cdc15 to phosphorylate the critical Ser-374 and Thr-544 phosphoacceptor sites of Dbf2 [3].
• Saccharomyces cerevisiae Mob1p is required for cytokinesis and mitotic exit [4].
• We found that the expression of MOB1 is also cell cycle regulated, its expression peaking slightly before that of DBF2 at the G2/M boundary [5].

Biological context of MOB1

• MOB1, an essential yeast gene required for completion of mitosis and maintenance of ploidy [6].
• Conditional alleles of MOB1 cause a late nuclear division arrest at restrictive temperature [6].
• We also examined the subcellular distribution of Mob1p during the cell cycle and found that Mob1p first localized to the spindle pole bodies during mid-anaphase and then localized to a ring at the bud neck just before and during cytokinesis [4].
• One mob1 strain, which maintains stable haploidy at both permissive and restrictive temperature, diploidizes at permissive temperature when combined with the mps1-1 mutation [6].
• In contrast, overexpression of MOB1 suppressed phenotypes associated with a dbf2-deleted strain and suppressed the lethality associated with a dbf2 dbf20 double deletion [5].

Associations of MOB1 with chemical compounds

• Moreover, Mob1p, but not Cdc15p, is required for dissociating Aurora from the kinetochore region [7].
• RESULTS: Using a combination of peptide library selection, phosphorylation of optimal peptide variants, and screening of a phosphosite array, we found that Dbf2-Mob1 preferentially phosphorylated serine over threonine and required an arginine three residues upstream of the phosphorylated serine in its substrate [8].

Physical interactions of MOB1

• DBF2 binds MOB1 in vivo and can bind it in vitro in the absence of other yeast proteins [5].

Regulatory relationships of MOB1

• We also demonstrate that mob1p can be precipitated from cells in a complex with the septation regulating kinase sid2p [9].

Other interactions of MOB1

• Mob1p contains no known structural motifs; however MOB1 is a member of a conserved gene family and shares sequence similarity with a nonessential yeast gene, MOB2 [6].
• Mob1p is a phosphoprotein in vivo and a substrate for the Mps1p kinase in vitro [6].
• These results are consistent with DBF2 acting through MOB1 and aiding in its function [5].
• Protein kinase Cdc15 activates the Dbf2-Mob1 kinase complex [3].

Analytical, diagnostic and therapeutic context of MOB1

• Here, we demonstrate that, in addition to mitotic exit, S. cerevisiae MEN gene MOB1 is required for cytokinesis and cell separation [4].

References