1. A protein factor promoting the binding of initiator tRNA to the 40S ribosomal subunit was purified to homogeneity (more than 2500-fold) from rat liver cytosol. It has a mol.wt. of 265000 and is composed of four subunits of identical molecular weight. 2. This factor directs the binding of methionyl-tRNA(fMet) and to a lesser extent also of N-acetylphenylalanyl-tRNA, but not of methionyl-tRNA(...

Transcription from the core promoter of the juvenile hormone esterase gene (-61 to +28) requires the presence of both an AT-rich motif (TATA box) and an initiator motif for any transcription to occur, when assayed by either transcription in vitro with lepidopteran Sf9 nuclear extracts or by transient-transfection assay in Sf9 cells. Additional gel-shift experiments indicated that at least one a...

Although many bacterial chromosomes require only one replication initiator protein, e.g., DnaA, most plasmid replicons depend on dual initiators: host-encoded DnaA and plasmid-encoded Rep initiator protein for replication initiation. Using the plasmid pSC101 as a model system, this work investigates the biological rationale for the requirement for dual initiators and shows that the plasmid-enco...

Introduction The assembly of precisely timed nucleoprotein structures comprising an initiator protein bound to a chromosomal origin of replication ensures that initiation of DNA synthesis at each origin occurs only once per cell cycle. The origin recognition complex (ORC) present at a chromosomal origin in yeast Sachromyces cerevisiae is one of the well studied example of such nucleoprotein str...

Vitronectin in a cell-adhesion molecule whose expression is temporally and spatially regulated in vivo, but whose regulatory mechanism of transcription is unknown. In this study, we characterized the mouse vitronectin gene promoter. Luciferase expression vectors cloned the successive 5'- or 3'-deletions of the 5'-flanking region upstream of the luciferase gene and were transfected into the huma...

We show that the absence of a Watson-Crick base pair at the end of the amino acid acceptor stem, which is a hallmark of all prokaryotic initiator tRNAs, is one of the key features that prevents them from acting as an elongator in protein synthesis. We generated mutants of Escherichia coli formylmethionine tRNA that have a base pair at the end of the acceptor stem. The mutants generated were C1-...

The aim of the study was to monitor the influence of increasing initiator concentrations on the properties of poly-N-isopropylacrylamide (polyNIPA) nanoparticles obtained via surfactant free precipitation polymerization (SFPP). In all studied systems P-001 to P-1, the same amount of monomer was used, and increasing amounts of potassium persulphate (KPS). The course of each reaction was monitore...

Non-aqueous microgel particles are commonly synthesised in water, dried, and then redispersed in non-aqueous solvents. An important factor to consider when synthesising such particles is the initiator, which can determine how well the particles disperse in solvents. Polystyrene microgel particles were made with three different initiators. When a neutral, oil soluble initiator (azobisisobutyroni...

Cytoplasmic initiator tRNAs from plants and fungi possess an unique 2'-phosphoribosyl residue at position 64 of their sequence. In yeast tRNA(iMet), this modified nucleotide located in the T-stem of the tRNA is a 2'-1''-(beta-O-ribofuranosyl-5''-phosphoryl)-adenosine. The phosphoribosyl residue of this modified nucleoside was removed chemically by treatment involving periodate oxidation of tRNA...