Abstract: Byr2 is a member of the growing family of MAP kinase kinase kinases, proteins that phosphorylate and activate MAP kinase kinases. Byr2 is required for sexual differentiation in Schizosaccharomyce pombe(S. pombe). Genetic and molecular studies have demonstrated that the kinase functions downstream of both Ras1 (a Ras oncoprotein homologue) and Gpa1 which is a homologue of mammalian heterotrimeric G protein α subunits, and upstream of Byr1, which is an S. pombe MAP kinase kinase Mek homologue. Ras1 and Byr2 interact physically, suggesting that Byr2 is an effector of Ras1 signaling in S. pombe. With regard to the domain structure, the N-terminal region is believed to constitute a regulatory domain, because expression of a truncated mutant (lacking 389–606) inhibits the sexual response in S. pombe. Deletion of 1–320 results in a hyperactive mutant. The sequence QRPPSE (207–212) is conserved in the N-terminal region of S. cerevisiae Ste11, which is structurally and functionally related to Byr2. Substitution of P209 (and its equivalent in Ste11) results in hyperactivation. Byr2 is most closely related both structurally and functionally to Saccharomyces cerevisiae (S. cerevisiae) Ste11. It is also related to S. cerevisiae Bck1, Mek kinase from mouse, and NPK1 from tobacco.
Publication Year: 1995
Publication Date: 1995-01-01
Language: en
Type: book-chapter
Indexed In: ['crossref']
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