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Possible involvement of differential splicing in regulation of the activity of Arabidopsis ANP1 that is related to mitogen‐activated protein kinase kinase kinases (MAPKKKs)
Author(s) -
Nishihama Ryuichi,
Banno Hiroharu,
Kawahara Emi,
Irie Kenji,
Machida Yasunori
Publication year - 1997
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1997.12010039.x
Subject(s) - map2k7 , biology , map kinase kinase kinase , c raf , mitogen activated protein kinase kinase , cyclin dependent kinase 9 , protein kinase a , ask1 , cyclin dependent kinase 2 , kinase , mitogen activated protein kinase , cyclin dependent kinase 4 , intron , sh3 domain , map3k7 , microbiology and biotechnology , genetics , gene , proto oncogene tyrosine protein kinase src
Summary Three types of Arabidopsis cDNA (cANP1, cANP2 and cANP3) have been isolated that encode putative protein kinases, designated ANP1, ANP2 and ANP3. These kinases exhibit a high degree of hornology to NPK1, a tobacco protein that is a member of the family of mitogen‐activated protein kinase kinase kinases (MAPKKKs), which appears to function in the proliferation of tobacco cells. The predicted amino acid sequences of the kinase domains in the amino‐terminal halves of the ANPs were more than 80% identical to that of NPK1, while the kinase‐unrelated regions in the carboxy‐terminal halves exhibited relatively low homology. Two species of cANP1 were identified, ANP1L cDNA (cANPIL) and ANP1S cDNA (cANP1S), which were derived from a single ANP1 gene: the former had an intron‐like sequence in the coding region for the kinase‐unrelated region, while the latter did not include such an intron‐like sequence. cANP1L encoded a putative protein with both kinase and kinase‐unrelated domains, resembling NPK1, whereas cANPIS encoded only the amino‐terminal kinase domain because the intron‐like sequence was absent, with resulting elimination of most of the kinase‐unrelated region. Genetic analysis with mutant yeast cells showed that over‐expression of cANPIL or of cANPIS activated the mating pheromone‐responsive signal pathway which is mediated by a MAP kinase cascade. Moreover, the extent of such activation by cANPIS was greater than that by cANPIL. These results predict that differential splicing of the intron‐like sequence in the ANP1 transcript might be at least one of the molecular mechanisms involved in the generation of active ANP1 protein kinase.