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Biomedical subjects

N Giocanti

Publications and source records attributed to N Giocanti.

23 records · Page 2Linked to original sources
PubMed1980

Radiochemical cross-linking of proteins to RNA within ribosomal subunits from E. colil MRE 600.

Irradiation in vitro of 30S and 50S ribosomal subunits from E. coli MRE 600 by gamma rays from cobalt 60, in the absence of oxygen, results in the formation of covalent links between the RNAs and some ribosomal proteins. At low radiation doses, just sufficient to keep the integrity of the ribosome structure, the phenomenon appears highly specific. In the 30S irradiated particle, protein S1 attaches to 16S RNA; in the 50S irradiated particle, the proteins L3, L13, L19, L21, L22 and L24 are linked to 23S RNA. The mechanism of formation of these cross-links and their contribution to the study of the tridimensional ribosome structure are also discussed.

Animals↗
PubMed1977

[Formation of covalent linkages between the nucleic acid and protein constituents of E. coli MRE 600 ribosomes during gamma irradiation].

Gamma-irrdiation of E. coli MRE 600 ribosomes in aqueous suspensions leads to covalent linkages between the RNA and some ribosomal proteins. The presence of oxygen during the irradiation strongly inhibits this phenomenon. It appears clearly that only a few proteins are able to participate in these cross-linking reactions, which occur simultaneously in the two sub-units. The radiochemical yield was determined at several concentrations and was relatively low.

Bacterial Proteins↗
PubMed1976

[Formation, by gamma irradiation, of RNA-protein cross-links in E. coli ribosomes].

Gamma irradiation in desaerated conditions of E. coli MRE 600 ribosomes, labelled with C14 uracil, leads to a decrease of extractibility of C14 RNA by lithium chloride 4 M-urea 8 M. On the other hand, the radioactivity of the protein fraction increases with irradiation. These results strongly suggest that RNA-protein cross links are formed in irradiated ribosomes.

Bacterial Proteins↗
PubMedDate not supplied

[DNA-dependent protein kinase (DNA-PK), a key enzyme in the re-ligation of double-stranded DNA breaks].

Repair pathways of DNA are now better defined, and some important findings have been discovered in the last few years. DNA non-homologous end-joining (NEHJ) is a crucial process in the repair of radiation-induced double-strand breaks (DSBs). NHEJ implies at least three steps: the DNA free-ends must get closer, preparation of the free-ends by exonucleases and then a transient hybridisation in a region of DNA with weak homology. DNA-dependent protein kinase (DNA-PK) is the key enzyme in this process. DNA-PK is a nuclear serine/threonine kinase that comprises three components: a catlytic subunit (DNA-PKCS) and two regulatory subunits, DNA-binding proteins, Ku80 and Ku70. The severe combined immunodeficient (scid) mice are deficient in DNA-PKCS: this protein is involved both in DNA repair and in the V(D)J recombination of immunoglobulin and T-cell receptor genes. It is a protein-kinase of the P13-kinase family and which can phosphorylates Ku proteins, p53 and probably some other proteins still unknown. DNA-PK is an important actor of DSBs repair (induced by ionising radiations or by drugs like etoposide), but obviously it is not the only mechanism existing in the cell for this function. Some others, like homologous recombination, seem also to have a great importance for cell survival.

Androstadienes↗