In the fall of 1944, I enrolled at the Hebrew University of Jerusalem. The student body numbered about 700 and the choice of faculties was somewhat limited.My hopewas to study medicine, but the plans to open a medical school were still at the drawing board stage. I therefore chose to study chemistry with biochemistry and bacteriology as minor subjects, which I thought I would need later if I we...

The incorporation of labeled precursors into ribonucleic acid with cell-free preparations of animal tissues has been observed in a number of laboratories (l-lo). Further studies with partially purified preparations indicate that the proximate precursors are nucleoside trirather than diphosphates (24). These enzyme preparations, unlike deoxyribonucleic acid polymerase (11-13) or polynucleotide p...

The total amount of noncoding sequences on chromosomes of contemporary organisms varies significantly from species to species. We propose a hypothesis for the origin of these noncoding sequences that assumes that (i) an approximately equal to 0.55-kilobase (kb)-long reading frame composed the primordial gene and (ii) a 20-kb-long single-stranded polynucleotide is the longest molecule (as a geno...

Several publications from this laboratory have dealt in a preliminary fashion with the preparation and properties of highly purified polynucleotide phosphorylase from Azotobacter vinelan&i (2-4). A more detailed account of this work is presented in thii paper. Although polynucleotide phosphorylase preparations can catalyze the synthesis of a variety of homopolymers (polyadenylic acid, polyuridy...

Polynucleotide DNA and RNA editing enzymes alter nucleic acid sequences and can thereby modify encoded informational content. Two major families of polynucleotide editing enzymes, the AID/APOBEC cytidine deaminases (which catalyze the deamination of cytidine to uridine) and the adenosine deaminases acting on RNA (ADARs, which catalyze the deamination of adenosine to inosine), function in a vari...

The purpose of this paper is to review certain aspects of the mechanism of action of polynucleotide phosphorylase and to present, rather briefly, some recent findings. The discussion will be concerned with studies carried out by S. Ochoa and his associates a t New York University, New York, N. Y., and with work done a t the National Institutes of Health. Reference will also be made to some rece...

In a cell, an enormous amount of energy is channelled into the biogenesis of ribosomal RNAs (rRNAs). In a multistep process involving a large variety of ribosomal and non-ribosomal proteins, mature rRNAs are generated from a long polycistronic precursor. Here, we show that the non-ribosomal protein Nol9 is a polynucleotide 5'-kinase that sediments primarily with the pre-60S ribosomal particles ...