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The binding of monoribosomes, oligoribosomes and polyribosomes to reticular membranes from rat liver.

ABSTRACT: 1. The activity of the enzyme protein disulphide-isomerase (EC 5.3.4.1) was used to measure the binding of ribosomal fractions to reticular membranes from the liver of unstarved male rats. 2. Membranes degranulated by treatment with KCl plus puromycin and washed by centrifugation through 0.5 M-KCl bound oligoribosomes but not monoribosomes. 3. Substitution of 0.25 M-KCl for 0.5 M-KCl in the wash solution produced membranes that bound monoribosomes and 60 S subunits in addition to oligoribosomes. 4. The binding of all classes of ribosomes to smooth and 'lightly granulated' rough membranes was activated by oestradiol. The hormone activation was much greater with polyribosomes from fed rats than for monoribosomes or oligoribosomes from starved rats. 5. Exposure of rough membranes to centrifugal forces caused them to undergo partial degranulation, as demonstrated by unmasking of protein disulphide-isomerase activity.

SUBMITTER: Fielder JA

PROVIDER: S-EPMC1185668 | biostudies-literature | 1978 Apr

REPOSITORIES: biostudies-literature

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The binding of monoribosomes, oligoribosomes and polyribosomes to reticular membranes from rat liver.

Fielder J A JA Dani H M HM Ridge D D Rabin B R BR

The Biochemical journal 19780401 1

1. The activity of the enzyme protein disulphide-isomerase (EC 5.3.4.1) was used to measure the binding of ribosomal fractions to reticular membranes from the liver of unstarved male rats. 2. Membranes degranulated by treatment with KCl plus puromycin and washed by centrifugation through 0.5 M-KCl bound oligoribosomes but not monoribosomes. 3. Substitution of 0.25 M-KCl for 0.5 M-KCl in the wash solution produced membranes that bound monoribosomes and 60 S subunits in addition to oligoribosomes. ...[more]

PMID: 656064

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Project description:This study examines the structural relationship of mitochondria and the endoplasmic reticulum in liver. Livers of rat and Japanese quail were homogenized and fractionated in media of 0.25 M-sucrose, either 5mM or 50 mM in sodium Hepes [4-(2-hydroxyethyl)-1-piperazine-ethanesulphonic acid], pH 7.4 (2.2 mM or 22 mM in Na respectively), designated here as low- and high-salt media. Three particulate fractions were prepared by sequential centrifugation. A nuclear pellet sedimenting at 300 g was obtained as described by Shore & Tata [(1977) J. Cell Biol. 72, 714-725], and from the resulting supernatant thereof a low-speed pellet (1100-1500 g) and a high-speed pellet (8000-10 000 g) were prepared. In the low-salt medium the yields of mitochondrial matrix enzymes (citrate synthase, glutamate dehydrogenase, ornithine carbamoyltransferase) and their specific activities in the low-speed pellet were over twice those in the high-speed pellet. In the high-salt medium the yield of matrix enzymes was 4-5 times, and the specific activities were up to 3 times, higher in the low-speed pellet than in the high-speed pellet. Oxygen uptake and respiratory control ratio were also much higher in the low-speed pellets in both media. Some 50-65% of the microsomal marker enzyme glucose 6-phosphatase was in the supernatant from the high-speed pellet, and the rest sedimented with the mitochondria. Repeated washing with the high-salt medium removes only a limited amount of reticulum. Washing with salt-free sucrose removes most of the reticulum, but a fraction remains strongly bound to mitochondria. Homogenates from quail and rat liver were fractioned isopycnically on Percoll gradients in either 0.25 M-sucrose or 0.25 M-sucrose/50 mM-sodium Hepes. Up to five particulate bands were separated and assayed. Mitochondria were present in two to three bands and were associated with endoplasmic reticulum. As seen in the phase-contrast microscope the mitochondria prepared in the low-salt medium consist of separate organelles. In the high-salt medium the mitochondria appear as chains of from three to ten organelles not touching each other. On addition of univalent ions at concentrations above 20 mM, the mitochondria aggregate into chains, and at higher ionic strength larger multidimensional aggregates are formed. The dispersion and aggregation of mitochondria are reversible. Negatively stained electron micrographs reveal a branched mitochondrial structure, with mitochondria held together by strands of reticulum.(ABSTRACT TRUNCATED AT 400 WORDS)

Dataset Information

The binding of monoribosomes, oligoribosomes and polyribosomes to reticular membranes from rat liver.

Publications

The binding of monoribosomes, oligoribosomes and polyribosomes to reticular membranes from rat liver.

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