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P Westermann

Publications and source records attributed to P Westermann.

68 records · Page 4Linked to original sources
PubMed1976

Studies on proteins of animal ribosomes. XXIV. Localisation of proteins in ribosomal subunits of rat liver studied by chemical substitution with p-nitrophenyl acetate and methyl acetimidate.

The reaction of [3H]p-nitrophenyl acetate (NPA) or [14C]methyl acetimidate (MAI) with amino groups of ribosomal pade between the reactivity of the proteins in situ in the ribosomal subunit with that of isolated protein mixtures. In the small subunit reactivity compared with the protein mixture was only 10-65% in the case of NPA but 45 to more than 100% in the case of MAI. In the large subunit reactivity to MAI was 10-60% that of the isas a denser structure than the small one. In agreement with earlier experiments with iodoacetamide the proteins S2, 5, 7, 8, 10 and 13 of the small subunit and L15, 17, 20, 24, 25, 27, 29, 33, 34, 35 and 38 in the large subunit are quite accessible while proteins S9, 14, 19, 20, 24, 25, 27, 29 and 30 of the small subunit and L1, 7, 8, 10, 11, 19, 28, 31, and 32 of the large one are relatively inaccessible.

Acetates↗
PubMed1976

Proteins of animal ribosomes. XXV. Proteins of rat liver ribosomes protected by polyuridylic acid from methyl acetimidate substitution.

Addition of poly(U) to complexes of 40S and 60S subunits of rat liver ribosomes decreases the substitution of amino groups of 12 proteins of the small ribosomal subunit and of 11 proteins of the large subunit by [14C]-methyl acetimidate. When comparing the results obtained with this amino group specific reagent with the reactivity of the proteins against iodoacetamide it becomes obvious that 4 proteins of the small ribosomal subunit (S12, 18, 19, 24) and 3 proteins of the large one (L20, 22, 25) are partially protected by poly(U) against reaction with both reagents.

Animals↗
PubMed1975

Changes in the reactivity of proteins of rat liver ribosomes against [14Ciodoacetamide depending on their organization in ribosomal subparticles, 80S ribosomes and on the attachment of poly-(U).

(1) The isolated mixtures of ribosomal proteins can be substituted by [14C]-iodoacetamide up to an average of about 2 equivalents per 20,000 dalton. The extent of substitution of single proteins measured after two-dimensional polyacrylamide gel electrophoresis shows that all proteins are reactive. (2) Also in the subunits, all proteins are accessible to substitution. Compared with isolated proteins, however, the reactivity is decreased and the amount of labelling for most proteins ranges as low as 5 to 20%. (3) Reassociation of ribosomal subunits decreases the reactivity of 12 proteins of the small subunit and that of 20 proteins of the large subunit. (4) The presence of messenger inhibits the substitution of 10 proteins of the small subunit and of 6 proteins of the large one. (5) Seven proteins of the small subunit and 3 proteins of the large one are influenced both by the other subunit and by messenger-RNA.

Animals↗