The genomes of diploid organisms in natural populations are highly polymorphic for insertions and deletions. During meiosis double-strand breaks (DSBs) that form within such polymorphic regions must be repaired by inter-sister chromatid exchange, rather than by inter-homolog exchange. Molecular-level studies of recombination during budding yeast meiosis have shown that recombination events initiated by DSBs in regions that lack corresponding sequences in the homolog are efficiently repaired by inter-sister chromatid recombination.[4] This recombination occurs with the same timing as inter-homolog recombination, but with reduced (2- to 3-fold) yields of joint molecules.
MAP2K1 is also known as MEK1 (see Mitogen-activated protein kinase kinase). MEK1 is a meiotic chromosome-axis-associated kinase that is thought to slow down, but not entirely block, sister chromatidrecombination. Loss of MEK1 allows inter-sister DSB repair and also inter-sister Holliday junction intermediates to increase. Despite the normal activity of MEK1 in reducing inter-sister chromatid recombination, such recombination still occurs frequently during normal budding yeast meiosis (although not as frequently as during mitosis), and up to one-third of all recombination events are between sister chromatids.[4]
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↑Yung, Y; Yao Z; Hanoch T; Seger R (May 2000). "ERK1b, a 46-kDa ERK isoform that is differentially regulated by MEK". J. Biol. Chem. UNITED STATES. 275 (21): 15799–808. doi:10.1074/jbc.M910060199. PMID10748187.
↑Zheng, C F; Guan K L (Nov 1993). "Properties of MEKs, the kinases that phosphorylate and activate the extracellular signal-regulated kinases". J. Biol. Chem. UNITED STATES. 268 (32): 23933–9. PMID8226933.
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↑Robinson, Fred L; Whitehurst Angelique W; Raman Malavika; Cobb Melanie H (Apr 2002). "Identification of novel point mutations in ERK2 that selectively disrupt binding to MEK1". J. Biol. Chem. United States. 277 (17): 14844–52. doi:10.1074/jbc.M107776200. PMID11823456.
↑Xu Be, Be; Stippec S; Robinson F L; Cobb M H (Jul 2001). "Hydrophobic as well as charged residues in both MEK1 and ERK2 are important for their proper docking". J. Biol. Chem. United States. 276 (28): 26509–15. doi:10.1074/jbc.M102769200. PMID11352917.
↑Chen, Z; Cobb M H (May 2001). "Regulation of stress-responsive mitogen-activated protein (MAP) kinase pathways by TAO2". J. Biol. Chem. United States. 276 (19): 16070–5. doi:10.1074/jbc.M100681200. PMID11279118.
↑Karandikar, M; Xu S; Cobb M H (Dec 2000). "MEKK1 binds raf-1 and the ERK2 cascade components". J. Biol. Chem. UNITED STATES. 275 (51): 40120–7. doi:10.1074/jbc.M005926200. PMID10969079.
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