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Rie Nakajima

Publications and source records attributed to Rie Nakajima.

6 recordsLinked to original sources
PubMed2004

Preparation of Escherichia coli cell extract for highly productive cell-free protein expression.

As structural genomics and proteomics research has become popular, the importance of cell-free protein synthesis systems has been realized for high-throughput expression. Our group has established a high-throughput pipeline for protein sample preparation for structural genomics and proteomics by using cell-free protein synthesis. Among the many procedures for cell-free protein synthesis, the preparation of the cell extract is a crucial step to establish a highly efficient and reproducible workflow. In this article, we describe a detailed protocol for E. coli cell extract preparation for cell-free protein synthesis, which we have developed and routinely use. The cell extract prepared according to this protocol is used for many of our cell-free synthesis applications, including high-throughput protein expression using PCR-amplified templates and large-scale protein production for structure determinations.

Cell Fractionation↗
PubMed2004

Patent protection for protein structure analysis.

Three national patent offices have consulted on patents that cover protein three-dimensional structural data and pharmacophores, with significant implications for the biotechnology industry.

Biotechnology↗
PubMed2002

Role of regucalcin as an activator of sarcoplasmic reticulum Ca2+-ATPase activity in rat heart muscle.

The expression of regucalcin, a regulatory protein of Ca(2+) signaling, and its effect on Ca(2+) pump activity in the microsomes (sarcoplasmic reticulum) of rat heart muscle was investigated. The expression of regucalcin mRNA was demonstrated by reverse transcription-polymerase chain reaction (RT-PCR) analysis in heart muscle using rat regucalcin-specific primers. Results with Western blot analysis showed that regucalcin protein was present in the cytoplasm, although it was not detected in the microsomes. Microsomal Ca(2+)-ATPase activity was significantly increased in the presence of regucalcin (10(-10)-10(-8) M) in the enzyme reaction mixture. This increase was not seen in the presence of thapsigargin (TP) (10(-5) M), a specific inhibitor of the microsomal Ca(2+) pump enzyme. Regucalcin (10(-10)-10(-8) M) significantly stimulated ATP-dependent (45)Ca(2+) uptake by the microsomes. The effect of regucalcin (10(-8) M) in increasing microsomal Ca(2+)-ATPase activity was completely prevented in the presence of digitonin (10(-3) or 10(-2)%), which has a solubilizing effect on membranous lipid, or N-ethylmaleimide (NEM), a modifying reagent of sulfhydryl (SH) groups. Dithiothreitol (DTT; 5 mM), a protecting reagent of SH groups, increased markedly Ca(2+)-ATPase activity. In the presence of DTT (5 mM), regucalcin could not significantly enhance the enzyme activity. Also, the effect of regucalcin in increasing Ca(2+)-ATPase activity was completely inhibited by the addition of vanadate (1 mM), an inhibitor of phosphorylation of enzyme. In addition, the effect of regucalcin on Ca(2+)-ATPase activity was not significantly modulated in the presence of dibutyryl cyclic AMP (10(-4) M), inositol 1,4,5-trisphosphate (10(-3) M), or calmodulin (5 microg/ml) which is an intracellular signaling factor. The present study demonstrates that regucalcin can activate Ca(2+) pump activity in rat heart microsomes, and that the protein may act the SH groups of Ca(2+)-ATPase by binding to microsomal membranes.

Animals↗
PubMed2002

Role of endogenous regucalcin in transgenic rats: suppression of kidney cortex cytosolic protein phosphatase activity and enhancement of heart muscle microsomal Ca2+-ATPase activity.

Rats were generated by pronuclear injection of the transgene with a cDNA construct encoding rat regucalcin that is a regulatory protein of Ca2+ signaling. Transgenic (TG) founders were fertile, transmitted the transgene at the expected frequency, and bred to homozygote. Western analysis of the cytosol prepared from the tissue of TG female rats (5-week-old) showed a remarkable expression of regucalcin (3.3 kDa) protein in the liver, kidney cortex, heart, lung, stomach, brain, spleen, muscle, colon, and duodenum. Regucalcin expression of TG male rats was seen in the liver, kidney cortex, heart, and lung. In wild-type (wt) male and female rats, regucalcin was mainly present in the liver and kidney cortex. Regucalcin inhibited protein phosphatase activity in rat kidney cortex cytosol and activated Ca2+-ATPase activity in rat heart muscle microsomes. The suppressive effect of regucalcin on protein phosphatase activity was significantly enhanced in the cytosol of kidney cortex of TG male and female rats as compared with those of wt rats. Likewise, heart muscle microsomal Ca2+-ATPase activity was significantly enhanced in TG rats. The changes in their enzyme's activities in TG rats were completely abolished in the presence of anti-regucalcin monoclonal antibody (100 ng/ml) in the enzyme reaction mixture. Moreover, the body weight of TG female rats was significantly lowered as compared with that of wt rats. Serum inorganic phosphorus concentration was significantly increased in TG male and female rats, while serum calcium, glucose, triglyceride, free cholesterol, albumin, and urea nitrogen concentrations were not significantly altered in TG rats. Regucalcin TG rats should be a useful model to define a regulatory role of endogenous regucalcin in the tissues in vivo.

Animals↗