Isolation and properties of polyribosomes and fragments of the endoplasmic reticulum from rat liver

1. A centrifugation method for the fractionation of the postmitochondrial fraction from rat-liver homogenates is described. The technique, in which no detergent is used, may be used as a tool to discriminate between two classes of ribosomes. One class is firmly bound to membranes and the other consi...

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Bibliographic Details
Published in:Biochemical journal 1967-04, Vol.103 (1), p.177-182
Main Authors: Bloemendal, H, Bont, W S, de Vries, M, Benedetti, E L
Format: Article
Language:English
Subjects:
Animals
Carbon Isotopes
Endoplasmic Reticulum - analysis
Leucine - metabolism
Liver - analysis
Liver - cytology
Male
Membranes
Microscopy, Electron
Phenylalanine - metabolism
Phospholipids - analysis
Proteins - analysis
Rats
Ribonucleases - analysis
Ribosomes - analysis
RNA - analysis
Starvation
Ultracentrifugation
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Summary:1. A centrifugation method for the fractionation of the postmitochondrial fraction from rat-liver homogenates is described. The technique, in which no detergent is used, may be used as a tool to discriminate between two classes of ribosomes. One class is firmly bound to membranes and the other consists either of free polysomes or of ribosomes attached by weaker forces to the membranes of the endoplasmic reticulum. 2. Electron-micrograph studies revealed that the polysomes were not contaminated with bound ribosomes or with membranous fragments. 3. The separated fractions were characterized by their RNA, protein, ribonuclease and phospholipid content. 4. The influence of starvation on the RNA and protein contents of the different fractions was investigated. 5. Labelling of the various centrifugal fractions in vivo revealed no difference in uptake of radioactive amino acid between the two classes of ribosomes. 6. Incorporation of radioactive leucine in vitro and the polyuridylic acid-directed phenylalanine incorporation were similar for both classes of ribosomes.
ISSN:0264-6021
1470-8728
DOI:10.1042/bj1030177