Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:3.1.26.9 (ribonuclease)
 6,589 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Three procedures for isolating ribonucleoprotein particles from the cytoplasmic fraction of rat-uterus homogenates are described. By procedure 1, ribonucleoprotein particles were isolated in the presence of 5mm-Mg(2+) and 25mm-K(+), and the postmitochondrial supernatant fraction was made to 1.3% (w/v) in potassium deoxycholate. About 50% of the RNA and protein of the microsomal fraction was recovered in the monomeric ribosomes isolated. By procedure 2, ribonucleoprotein particles were isolated in the presence of 10mm-Mg(2+) and 0.1m-K(+), and in the absence of detergent. The ribosomes obtained were primarily polymeric, but recovery of microsomal RNA and protein was only 32%. By procedure 3, ribonucleoprotein particles were isolated according to procedure 1 but without the use of detergent. A mixture of polymeric and monomeric ribosomes was obtained, and the recovery of microsomal RNA and protein was about 60%. 2. Uterine polymeric and monomeric ribosomes, isolated by procedure 3 and designated ;polyribosomal preparation', were examined for protein-synthesizing capabilities. The principal properties of the cell-free protein-synthesizing system containing the polyribosomal preparation are described. The efficiency of amino acid incorporation in the complete system incubated for 30min. and containing the polyribosomal preparation was found to be either 2.5 molecules of [(14)C]leucine or 2.2 molecules of [(14)C]-valine incorporated/ribosome. Assay of the preparation in the complete cell-free system containing 10mm-sodium fluoride indicated that 40% of the incorporation activity is a result of initiation of new polypeptide chains and 60% is due to completion of previously existing chains. Monomeric ribosomes obtained by various treatments of the polyribosomal preparation with sodium fluoride, ribonuclease and potassium deoxycholate had decreased incorporation activity in the cell-free system. However, monomeric ribosomes obtained by treatment with sodium fluoride only had an incorporation activity 50% greater than that of monomers obtained by treatment with ribonuclease only. 3. The results indicate that uterine polymeric and monomeric ribosomes are sites of amino acid incorporation in vivo and in vitro. It is concluded that most polymeric and monomeric ribosomes occurring in the cytoplasmic fraction of the uterus are free and unattached to membranes, and that the polyribosomes are relatively unstable.
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PMID:Regulation of polyribosome formation and protein synthesis in the uterus. Isolation of cytoplasmic ribonucleoprotein particles and the principal properties of the cell-free protein-synthesizing system. 1674 35

Here, we demonstrate that pancreatic microsomal membranes from pigs, sheep, or cattle destined for human consumption can be used as a valuable and ethically correct alternative to dog microsomes for cell-free protein translocation. By adding adequate ribonuclease (RNase) inhibitors to the membrane fraction, successful in vitro co-translational translocation of wild-type and chimeric pre-prolactin into the lumen of rough microsomes was obtained. In addition, the human type I integral membrane proteins CD4 and VCAM-1 were efficiently glycosylated in RNase-treated microsomes. Thus, RNase-neutralized pancreatic membrane fractions from pig, cow, or sheep are a cheap, easily accessible, and fulfilling alternative to canine microsomes.
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PMID:Ribonuclease-neutralized pancreatic microsomal membranes from livestock for in vitro co-translational protein translocation. 2605 Jun 31

Arabidopsis bZIP60 is a major transcription factor that activates the unfolded protein response and is regulated by cytoplasmic splicing. Two Arabidopsis inositol-requiring 1s (IRE1A and IRE1B) cleave bZIP60 mRNA; however, the ligase that connects the two half-molecules of the split bZIP60 mRNA has not yet been identified. We aimed to determine whether the Arabidopsis tRNA ligase RLG1 catalyzes the ligation of cleaved bZIP60 mRNA. Recombinant IRE1B containing the ribonuclease domain correctly cleaved synthetic RNA covering the cleaved site of bZIP60 in vitro. Recombinant RLG1 then ligated the two cleaved fragments. The cytoplasmic form of RLG1 was expressed in a T-DNA insertion mutant whose homozygote exhibited a lethal phenotype and when the transgene was substituted with endogenous RLG1, the plants grew normally. RLG1 proteins derived from transgene were mainly found in the cytoplasm; however, some were in the microsomal fraction, possibly on the ER membrane. This intracellular distribution of RLG1 is discussed.
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PMID:Arabidopsis tRNA ligase completes the cytoplasmic splicing of bZIP60 mRNA in the unfolded protein response. 2682 May 26


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