TY - JOUR
T1 - Purification and partial characterization of an acidic ribosomal protein kinase from maize
AU - Sepúlveda, Gabriela
AU - Aguilar, Raül
AU - Sánchez de Jiménez, Estela
PY - 1995/8
Y1 - 1995/8
N2 - 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 mM 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 (P2). Its activity is inhibited by Ca2+ and Zn2+ and is activated by Mg2+, polylysine and spermine. The relevance of this protein kinase in reinitiating the protein synthesis process during germination is discussed.
AB - 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 mM 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 (P2). Its activity is inhibited by Ca2+ and Zn2+ and is activated by Mg2+, polylysine and spermine. The relevance of this protein kinase in reinitiating the protein synthesis process during germination is discussed.
KW - Acidic ribosomal proteins
KW - phosphorylation
KW - protein kinase
KW - ribosomal proteins
UR - http://www.scopus.com/inward/record.url?scp=0028836318&partnerID=8YFLogxK
U2 - 10.1111/j.1399-3054.1995.tb00989.x
DO - 10.1111/j.1399-3054.1995.tb00989.x
M3 - Artículo
AN - SCOPUS:0028836318
SN - 0031-9317
VL - 94
SP - 715
EP - 721
JO - Physiologia Plantarum
JF - Physiologia Plantarum
IS - 4
ER -