[Recombinant murine cell lines, transformed by various vectors based on bovine type 1 papillomavirus and expressing human tissue plasminogen activator. II. Analysis of cell lines, producing recombinant tissue plasminogen activator]. / Rekombinantnye linii kletok myshi, transformirovannye raslichnymi vektorami na osnove bych'ego papillomavirusa tipa 1 i ékspressiruiushchie tkanevoi aktivator plazminogena cheloveka. II. Analiz kletochnykh linii, produtsiruiushchikh rekombinantnyi tkanevoi aktivator plazminogena.

We have characterized a number of recombinant cell lines established with BPV1 and Lx1 (containing duplication of LCR-E6-E7 sequence) vectors on the basis of C127 cells. It had been shown that Lx1 based vectors possess the higher number of intracellular copies than analogous vectors on the basis of wtBPV, and most part of them is integrated into the host genome. Using various concentrations of heavy metal salts we have developed the optimized procedure for induction of recombinant tPA synthesis which is controlled by the mouse MT1 promoter. A 8-fold increase of rtPA concentration was reached in the course of induction. It had been shown that native and non-glucosylated forms of recombinant and human tPA are identical in their properties.

[Expression of human tissue plasminogen activator by recombinant cell lines from various animals]. / Ekspressiia tkanevogo aktivatora plazminogena cheloveka rekombinantnymi liniiami kletok razlichnykh zhivotnykh.

A number of recombinant cell lines which produce human tissue plasminogen activator (tPA) was obtained using different hosts--mouse, rat, hamster, simian and human cell lines. All types of recombinant lines secreted active r-tPA into conditioned medium. A slight difference between molecular weights of secreted variants of r-tPA was mediated by the different mechanisms of protein modification. Treatment of some recombinant cell lines with different substances resulted in increased levels of r-tPA production.

[Protein L16 of the Escherichia coli ribosome: possible role in protein biosynthesis]. / Belok L16 ribosomy Escherichia coli: vozmozhnaia rol' v biosinteze belka.

We show that Escherichia coli 50S ribosomal subunits depleted of protein L16 can nevertheless catalyze the transfer of the peptide moiety from fMet-tRNA to puromycin, being, however, unable to use a fragment CACCA-Phe as an acceptor substrate. On the other hand, we found that protein L16 as well as its large fragment (amino acids 10-136) both interact with tRNA in solution (Kd approximately 10(-7) M). Moreover, L16 interacts with CACCA-Phe in solution as well as protects 3' end of tRNA from the enzymatic degradation. We suggest that L16, although not being the peptidyl transferase as such, is involved in the binding of the 3' end cytidines of tRNA into the ribosomal A site.

[Binding of Escherichia coli 50S ribosomal subunit proteins with two large 5S RNA fragments]. / Sviazyvanie belkov 50S subchastitsy ribosomy Escherichia coli s dvumia krupnymi fragmentami 5S RNK.

Two fragments containing sequences from 1-41 nucleotide (small fragment) and from 42-120 nucleotide (large fragment) were isolated from E. coli 5S RNA T1 RNase partial digest. Affinity chromatography of 50S ribosomal proteins on the immobilized 5S RNA fragments revealed the ability of the large fragment to give a complex only with protein L25. The small fragment did not bind ribosomal proteins. The intact and reassociated 5S RNA forms a complex consisting of proteins L5, L18, L25.