Search PubMed⌕ Search

Biomedical subjects

H Noll

Publications and source records attributed to H Noll.

36 records · Page 2Linked to original sources
PubMed1976

Cell surface alterations on colon adenocarcinoma cells.

By the use of five independent techniques, cell surface alterations distinctive of malignant as compared to normal colon cells were detected on in vivo surgical specimens and on cultured cell lines established in our laboratory. The findings, which were distinctive of the malignant as compared to the normal cell included: (a) polymorphism of surface microvilli on scan electron microscopy; (b) decreased susceptibility to infection with vaccinia and reovirus, but not to herpes, adeno- or echovirus: (c) production of large quantities of carcinoembryonic antigen; (d) presence of specific membrane proteins on sodium dodecyl sulfate-polyacrylamide gel analysis of plasma membranes purified from cell homogenates by ultracentrifugation in polyethylene glycol-dextran partitions; and (e) reaction with specific, cytotoxic, rabbit heteroantisera. Solubilized extracts of the malignant cells formed precipitin lines with the heteroantisera, suggesting that the distinctive antigens could be released from the cell surface. These results suggest that human colon carcinomas bear tumor-distinctive proteins and offer the prospect of specific immunodiagnostic reagents and immunotherapeutic tools.

Adenocarcinoma↗
PubMed1972

Initiation factor IF-3-dependent binding of Escherichia coli ribosomes and N-formylmethionine transfer-RNA to rabbit globin messenger.

An initiation complex has been formed in high yields from E. coli ribosomes, 9S messenger RNA for rabbit hemoglobin, and N-formylmethionine-tRNA. Initiation factor IF-3 is required for the binding and puromycin is required for the release of fMet. Valyl-tRNA fails to bind to the second codon, whereas a mixture of 15 aminoacyl-tRNAs promotes incorporation. Together with quantitative data, the findings suggest that IF-3 directs the ribosomes to an AUG codon on one of the two globin messengers, at a site that is different from the normal starting point for globin synthesis.

Acetates↗
PubMed1971

Conformational changes in ribosomes during protein synthesis.

In a purified system containing poly(U) and ribosomal subunits from Escherichia coli, and purified transfer factors T and G, the active ribosomal complex passes through a cycle of contraction and expansion with the addition of each amino acid; aminoacyl-tRNA binding catalyzed by T produces the stable compact state, corresponding to the 70S conformation, whereas translocation with G expands the ribosome to a less stable 60S form. It is also shown that formation of the first peptide bond must be preceded by translocation with G. These findings are consistent with a model of chain initiation in the absence of initiation factors in which deacylated tRNA(Phe) bound to the P site signals translocation by G and GTP as soon as the 60S initiation complex has been converted to the 70S form by the enzymatic binding of Phe-tRNA.

Bacterial Proteins↗
PubMed1966

Chain initiation and control of protein synthesis.

Analysis of the enzymatic mechanism of chain extension during protein synthesis and studies with N-formylmethionyl-sRNA suggest that chain initiation requires formylation of the amino group of the amino acid destined to start chain growth. The existence of a set of starting triplets coding for a special set of N-formylaminoacyl-sRNA's is postulated. These triplets might be ambiguous in the sense that they specify different amino acids, depending on whether they are at the beginning of or within a message. A number of starting triplets and their NH(2)-terminal amino acids are predicted from previously suggested ambiguities. The biochenmical, regulatory, and genetic implications of a formylation step controlling chain initiation are discussed.

Amino Acid Sequence↗