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U Maitra

Publications and source records attributed to U Maitra.

87 records · Page 5Linked to original sources
PubMed1971

A complex between initiation factor IF2, guanosine triphosphate, and fMet-tRNA: an intermediate in initiation complex formation.

Evidence is presented that suggests the formation of a complex between polypeptide chain-initiation factor IF 2, GTP, and fMet-tRNA(f). This complex transfers both fMet-tRNA(f) and GTP to 30S ribosomal subunits in the presence of ApUpG and initiation factor IF 1. The resultant 30S initiation complex reacts with 50S subunits to form a 70S initiation complex. fMet-tRNA(f) in this 70S complex reacts with puromycin to form fMet-puromycin. These results suggest that [IF 2, GTP, fMet-tRNA(f)] is an intermediate in the initiation of protein synthesis in Escherichia coli.

Adenosine Monophosphate↗
PubMed1971

Isolation and properties of polypeptide chain initiation factor FII from Escherichia coli: evidence for a dual function.

Initiation factor FII (F(3), factor B) has been purified from Escherichia coli Q13 to apparent homogeneity. It is a heat-stable basic protein, consisting of a single polypeptide chain of molecular weight 21,000. FII is required, in addition to the other factors FI and FIII, for the formation of a 70S complex containing fMet-tRNA, poly(U,G) (used as a model messenger RNA), and the ribosome. FII also is capable of dissociating 70S ribosomes to 30S and 50S subunits. Evidence is presented that both activities are mediated by the same protein.

Bacterial Proteins↗
PubMed1969

DNA-dependent synthesis of RNA by Escherichia coli RNA polymerase: release and reinitiation of RNA chains from DNA templates.

RNA synthesis in an in vitro RNA polymerase system at low ionic strength soon ceases, due to inhibition by accumulated RNA. Measurement of RNA chain initiation by the incorporation of gamma-(32)P-ATP and GTP with native T2 or T4 DNA as template shows that only one RNA chain is formed per molecule of enzyme added. In contrast, when the polymerase reaction is carried out in 10 mM Mg(++) and 0.2 M KCl, RNA synthesis proceeds nearly linearly for hours, resulting in a marked increase in accumulated RNA. Incorporation of gamma-(32)P-ATP also proceeds throughout the course of the reaction and the number of chains initiated per molecule of enzyme is increased severalfold. Most RNA chains formed are released from the DNA template as free RNA. Polymerase is released also in this process and acting catalytically reinitiates new chains. Rifampicin inhibits initiation of RNA synthesis and also blocks reinitiation of RNA chains without affecting growth of RNA chains already initiated.

Centrifugation, Zonal↗