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Purification and partial characterization of an acidic ribosomal protein kinase from maize
Author(s) -
Sepúlveda Gabriela,
Aguilar Raül,
Sánchez de Jiménez Estela
Publication year - 1995
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1995.tb00989.x
Subject(s) - biochemistry , ribosomal protein , protein kinase a , ribosome , polyacrylamide gel electrophoresis , centrifugation , gel electrophoresis , chromatography , chemistry , biology , microbiology and biotechnology , enzyme , rna , gene
Phosphorylation and dephosphorylation of ribosomal proteins have been suggested to participate in the regulation of protein synthesis in eukaryotic organisms. The present research focuses on the purification and partial characterization of a protein kinase from maize ribosomes that specifically phosphorylates acidic ribosomal proteins. Ribosomes purified from maize axes were used as the enzyme source. Purification of ribosomes was performed by centrifugation through a 0.5 M sucrose, 0.8 M KCl cushion. A protein kinase activity present in this fraction was released by extraction with 1.5 M KCl and further purified by diethylaminoethyl cellulose column chromatography. A peak containing protein kinase activity was eluted around 400 m M KCl. Analysis of this fraction by sodium dodecyl sulfate‐polyacrylamide gel electrophoresis showed one band of 38 kDa molecular mass, which cross‐reacted in a western blot with antibodies raised against proteins from the large ribosomal subunit. This enzyme specifically phosphorylates one of the acidic ribosomal proteins (P 2 ). Its activity is inhibited by Ca 2+ and Zn 2+ and is activated by Mg 2+ , polylysine and spermine. The relevance of this protein kinase in reinitiating the protein synthesis process during germination is discussed.