[Tissue-specific transcription of the gene for immunoglobulin kappa-chains in a cell-free system]. / Tkanespetsificheskaia transkriptsiia gena kappa-tsepei immunoglobulina v beskletochnykh sistemakh.

The x gene of immunoglobulin is effectively transcribed in extracts from homologous, i. e. lymphoid cells; the transcription is weak and incorrect in a heterologous system. x gene fragments with deletions in the 5'-region of the gene and with transpositions of the enhancer have been constructed. If the enhancer is removed, the transcription becomes weaker, although it remains tissue-specific. The transcription is weakened abruptly by removing a region preceding the CAT-box, in which the conservative TNATTTGCAT sequence is located. The transcription is tissue-specific due to a protein factor which is contained in the lymphoid cells. When this factor is repeatedly purified and added to an extract from HeLa cells, the transcription becomes much more effective and its initiation point is corrected. The transcription factor exerts a distinct action on templates with the native promoter, but the action decreases abruptly if the dc region of the gene is removed. The results indicate that the protein factor(s), which recognizes the DNA region preceding the CAT box, is necessary for the effective, tissue-specific and correct transcription of the x gene.

[Regulation of transcription of immunoglobulin kappa genes in Xenopus laevis oocytes]. / Reguliatsiia transkriptsii kappa-genov immunoglobulinov v ootsitakh shportsevoi liagushki.

Recombinant plasmids containing the immunoglobulin kappa gene with deletions in the 5' and 3' regions of the gene having different position and orientation of the enhancer element were constructed. The plasmids were incubated with cell-free extracts prepared from lymphoid and non-lymphoid cells, and then injected into the nuclei of Xenopus laevis oocytes. Tissue-specific transcription of the V kappa gene was shown to be under control of factor(s) existing in lymphoid cells. The data reported in this paper allow to suggest that, along with the positive transcription control regions located in the 5' region of the gene and in the J-C intron, there is also a negative control region situated in the J-C intron as well. Possible role of the tissue-specific factors from lymphoid cells is to abolish the negative control.

[Factors of tissue-specific transcription of immunoglobulin kappa genes]. / Faktory tkanespetsificheskoi transkriptsii kappa-genov immunoglobulinov.

Proteins TIF1 and TIF2 with mol mass 90 and 94 kD, respectively, were found in myeloma cells. They bind to the promoter region of the kappa genes. Protein TIF1 was found in nonlymphoid cells (HeLa, liver cells). From myeloma MPOC21 a fraction was isolated enriched 400 fold with TIF2 by fractionation on ion-exchangers DE52 and P11 and hydroxylapatite. The purified protein protected the DNA site that contained 30bp including the conservative sequence TNATTTGCAT located upstream of the kappa gene promoter against the action of DNAase. Addition of the purified factor to the extract from HeLa cells increased several fold the efficiency of transcription and corrected the initiation of transcription.

[The structure of the variable gene for the kappa chains of antibodies produced by hybridoma PTF-02]. / Struktura variabel'nogo gena kappa-tsepei antitel, produtsiruemykh gibridomoi PTF-02.

The genome of hybridoma PTF-02 has two genes for the kappa chains, and only one of these codes for the synthesis of the antibody light chains. The nucleotide sequences corresponding to the leader peptide and to the variable region of this gene were determined. An amino acid sequence corresponding to exons has been proposed on the basis of the nucleotide sequence. A nucleotide sequence adjacent to the gene at the 5'-end has also been determined, in particular, the precise localization of TATA- and CAT-boxes as well as those of the conservative deca (dc) and pentadeca (pd) sequences. The structure of the regulatory region in the gene is similar to that in the myeloma genomes. However, the 5'-region differs in its nucleotide composition and in the frequency of dc sequences from the DNA sequences adjacent to the 5'-end of eukaryotic genes which do not belong to the immunoglobulin family.

[Regulator sequences in the kappa-chain gene expressed in the hybridoma PTF.02]. / Reguliatornye posledovatel'nosti v gene kappa-tsepei, ékspressiruemov gibridome PTF.02.

Two kappa genes, one (5.7 kb) from parental myeloma cells that were used for fusion, and the other (7.5 kb) from lymphocytes have been detected in the genome of PTF.02 hybridoma. Functionally important regions of the second gene were sequenced. In the 5'-region, positions and nucleotide sequences of the L-fragment, TAATA- and CAAT-boxes were established. Deca (dc)- and pentadecanucleotide (pd) sequences, obligatory for effective transcription of Kappa genes, were localized at the distance of 91 and 118 bp from the ATG initiating codon of the leader sequence. Together with a true pd, a shadow pd sequence was localized. This sequence was overlapped with the first sequence and shifted by one helical twist. The structure of the region of the enhancer localization was established. Comparison of this sequence with known consensus of the papova virus enhancer allows us to suggest the following structure of the enhancer core for kappa chains: TGTGGCTAA... 10 bp... TGTGGTTA. In the kappa gene under study, the variable fragment is linked to the J5 segment. In the latter, a point mutation C----G was found, to which a conservative substitution Ala - Gly in a hypervariable region of the chi-chain should correspond. Somatic mutations were also observed within the intron region adjacent to the J5 segment.