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atpk1, a novel ribosomal protein kinase gene from Arabidopsis. II. Functional and biochemical analysis of the encoded protein.
Zhang, S H; Broome, M A; Lawton, M A; Hunter, T; Lamb, C J.
Afiliação
  • Zhang SH; Plant Biology Laboratory, Salk Institute for Biological Studies, La Jolla, California 92037.
J Biol Chem ; 269(26): 17593-9, 1994 Jul 01.
Article em En | MEDLINE | ID: mdl-8021267
The Arabidopsis Atpk1 protein expressed in insect cells and plant cells exhibited multiple sizes consisting mainly of two doublets: p70 (68 and 70 kDa) and p85 (82 and 85 kDa). Extraction of p85 from cells required the presence of SDS, suggesting that p85 is associated with less soluble subcellular components. p70 was extracted by nonionic detergent without SDS, indicating that this form is cytoplasmic. p70 expressed in either Arabidopsis or insect cells underwent serine-specific autophosphorylation, indicating that Atpk1 is a protein-serine kinase. A point mutation (lysine 163 to arginine) in the ATP-binding site of the catalytic domain substantially diminished activity when expressed in insect cells. A 14-kDa protein (p14) was co-immunoprecipitated with p70 from insect cells expressing wild-type Atpk1 and was phosphorylated in immune complex kinase assays with Atpk1, suggesting it is a homolog of a natural substrate of Atpk1. Two plant ribosomal proteins (14 and 16 kDa) can be phosphorylated by the Atpk1 protein kinase, and we propose that Atpk1 is a novel ribosomal protein kinase. A 60-kDa form of Atpk1 derived from the insect cell-expressed p70 was more highly phosphorylated than p70 in in vitro kinase assays, suggesting a negative regulatory domain can be removed by proteolysis.
Assuntos
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Proteínas de Plantas / Ribossomos / Proteínas Serina-Treonina Quinases / Arabidopsis / Proteínas de Arabidopsis Limite: Animals Idioma: En Ano de publicação: 1994 Tipo de documento: Article
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Coleções: 01-internacional Base de dados: MEDLINE Assunto principal: Proteínas de Plantas / Ribossomos / Proteínas Serina-Treonina Quinases / Arabidopsis / Proteínas de Arabidopsis Limite: Animals Idioma: En Ano de publicação: 1994 Tipo de documento: Article