scholarly journals Contamination of free-ribosome fractions by detached previously membrane-bound ribosomes (Short Communication)

1974 ◽  
Vol 138 (2) ◽  
pp. 305-307 ◽  
Author(s):  
K. O'Toole
Keyword(s):  
Rat Liver ◽  
Membrane Fraction ◽  
Short Communication ◽  
Free Ribosome ◽  
Membrane Bound ◽  
Free Polyribosome

A rough-membrane fraction isolated from rat liver by a procedure designed to prevent membrane denaturation was subjected to the gradient treatment normally used to isolate free ribosomes. Under these conditions, at most 20% of the ribosomes were detached from membrane with less than 5% sedimenting into the free-polyribosome pellet.

scholarly journals Preferential synthesis of a membrane-associated protein by free polyribosomes (Short Communication)

1973 ◽  
Vol 136 (3) ◽  
pp. 825-828 ◽  
Author(s):  
Dorrit Lowe ◽  
T. Hallinan
Keyword(s):  
Rat Liver ◽  
Alternative Explanation ◽  
Short Communication ◽  
Membrane Bound ◽  
Preferential Synthesis

Isolated free polyribosomes from rat liver appear to synthesize NADPH–cytochome c reductase in vitro four times as efficiently as do membrane-bound polyribosomes. The observed synthesis by the latter could result from contamination with free polyribosomes, but an alternative explanation is also suggested.

scholarly journals Polyribonucleotide synthesis by subfractions of microsomes from rat liver

1968 ◽  
Vol 109 (2) ◽  
pp. 229-238 ◽  
Author(s):  
N. M. Wilkie ◽  
R. M. S. Smellie
Keyword(s):  
Acetic Acid ◽  
Rat Liver ◽  
Transfer Rna ◽  
Light Fraction ◽  
Free Ribosome ◽  
Polyadenylic Acid ◽  
Insoluble Material ◽  
Polyuridylic Acid ◽  
Microsome Fraction

1. The microsome fraction of rat liver has been fractionated and the ability of the fractions to incorporate ribonucleotides into polyribonucleotides has been studied. Activity was found in the rough-surfaced vesicle (light) fraction and in the free-ribosome fraction and this latter activity has been examined. 2. The free-ribosome fraction contains ribosome monomers, dimers and trimers together with some higher oligomers and ferritin. In addition to catalysing the incorporation of ribonucleotides into acid-insoluble material it contains diesterase activity. It catalyses the incorporation of UMP from UTP, but not UDP, AMP from ATP and CMP from CTP into polyribonucleotide material, and for UTP the product appears to be a homopolymer not more than eight units long attached to the ends of primer polyribonucleotide strands. 3. The activity could not be removed from the free-ribosome fraction by washing or by isolation in the presence of ethylenediaminetetra-acetic acid. 4. Partially hydrolysed polyuridylic acid but not polyadenylic acid could serve as a primer for the incorporation of UMP, but some activity was always associated with an endogenous primer. 5. Analysis of RNA extracted from the free-ribosome fraction after incubation with [3H]UTP showed the presence of 28s, 18s, 5s and transfer RNA types, but no radioactivity was associated with any of these RNA fractions.

scholarly journals The molecular form of acetylcholinesterase as determined by irradiation inactivation (Short Communication)

1974 ◽  
Vol 137 (1) ◽  
pp. 123-125 ◽  
Author(s):  
S. R. Levinson ◽  
J. C. Ellory
Keyword(s):  
Molecular Weight ◽  
Short Communication ◽  
Molecular Form ◽  
Electric Organ ◽  
Molecular Size ◽  
Erythrocyte Ghosts ◽  
Multiple Forms ◽  
Electrophorus Electricus ◽  
Membrane Bound

The molecular size of acetylcholinesterase (EC 3.1.1.7) from the electric organ of Electrophorus electricus and erythrocyte ‘ghosts’ was estimated in both membrane-bound and purified preparations by irradiation inactivation. Results suggest that the form of the enzyme in the membrane is a monomer of molecular weight approx. 75000 and that multiple forms of the enzyme observed in solubilized preparations are aggregates of this monomer.

Sign in / Sign up

Export Citation Format

Share Document