[Identification of proteins in complexes with alpha-latrotoxin receptors].

A thorough analysis of proteins capable of interacting with presynaptic receptors of alpha-latrotoxin was carried out. The protein components of receptor complexes were isolated from rat brain membranes by affinity chromatography on immobilized alpha-latrotoxin and antibodies to the cytoplasmic moiety of the calcium-independent receptor of alpha-latrotoxin (CIRL) followed by analysis by mass spectrometry. Several proteins were identified, with structural proteins, intracellular signal proteins, and proteins involved in the endocytosis and transport of synaptic vesicles being among them.

[oct-genes and oct-proteins]. / oct-geny i oct-belki.

The review considers the functions and properties of Oct proteins, which belong to the POU family of transcription factors, and the roles of the POU and other domains in DNA recognition and interaction with other proteins of the transcription initiation complex. The structure and expression regulation of the oct genes are described with special emphasis on alternative transcription initiation from different promoters and alternative splicing, which result in several protein subforms.

[Regulation of human oct-1 gene transcription involves two promotors]. / Reguliatsiia transkriptsii gena oct-1 cheloveka s uchastiem dvukh promotorov.

Transcription initiation of human Oct-1 transcription factor-encoding gene involves two promoters, 1U and 1L, located at a substantial distance (about 100 kb) apart. The structure of these promoters and the adjacent sequences is different. Specifically, the 1U sequence is GC-rich, while the 1L sequence is AT-rich. Correspondingly, more than 25 GC-rich Sp1 cis-elements were localized within the 1U region, while in the 1L sequence nearly equal amount of homeo-specific NTAATNN sites along with two ATGCAAAT octamers were found. Analysis of transfection of recombinant plasmids, carrying the promoter fragments with or without enhancer indicated that expression from the 1L promoter was tissue-specific. In nonlymphoid HEK293 cells efficiency of transcription from the 1U promoter was several times higher than that from the 1L promoter. Another expression pattern was observed at transfection of the same constructs into Raji lymphoid cells. In this case the level of transcription from the L promoter (fragment L2) at the presence of external enhancer was higher than that from the fragments containing the 1U promoter. It was shown that the distal regions of 1U and 1L were capable of silencing activity. In Raji cells enhancer completely overcomes the activity of U silencer, but only partly overcomes the activity of L silencer. Our data on the interaction of two promoters with the enhancer and silencer in different cell types point to fine tissue-specific regulation of the oct-1 gene expression, especially in lymphatic cells.

[Spliced oct-1 gene mRNA isoforms with untranslated exons and a deletion in the region coding for the POU-specific domain]. / Splaisirovannye subformy mRNK gena oct-1, soderzhashchie netransliruemye ékzony i deletsiiu v oblasti POU-spetsificheskogo domena.

Transcription factor Oct-1 is involved in expression regulation of housekeeping genes, in lymphocyte differentiation, and in the immune response. Tissue-specific oct-1 mRNA isoforms are known to be expressed in lymphoid cells. Four new mouse isoforms were identified. Of these, two were tissue-specific (oct-1R alpha and oct-1R beta) and contained exon 1L. The oct-1R alpha was shown to contain an additional fragment, which corresponds to an exon located in the 3'-region of mouse otf-1. No homolog was found in human OTF-1. The oct-1R alpha isoform proved to lack an exon coding for a fragment of the POU domain. This deletion results in a loss of the first helix of the domain, and the mutant protein is devoid of affinity for octamer ATGCAAAT. Two other mRNA isoforms, oct-1d and oct-1e, were shown to contain untranslated regions between exons 1U and 2. The regions correspond to exons 1i and 2i located between exons 1U and 1L in the 5'-region of the mouse oct-1 gene. Human OTF-1 was not found to contain exon 1i. On evidence of these and published data, it was assumed that a set of oct-1 isoforms is present in the cell, reflecting the complexity of expression regulation of oct-1 and the multiplicity of its functions.

[Subforms of transcription factor Oct-1 synthesized in lymphocytes]. / Subformy faktora transkriptsii Oct-1, sinteziruemye v limfotsitakh.

Transcription factor Oct-1 is ubiquitous, participating in expression of the cell housekeeping genes as well as in differentiation of lymphocytes and activation of transcription of immunoglobulin genes in B cells. A new tissue-specific form of Oct-1 (Oct-1L) was found in lymphoid cells of bone marrow, lymph nodes, spleen, thymus, as well as in the cell lines of B and T lymphocytes at different stages of differentiation. This isoform was not found in embryonal and nonlymphoid tissues and cell lines. The complete structure of the oct-1L mRNA was determined, which generally corresponds to the structure of mouse Oct-1b. The difference between oct-1L and isoforms oct-a, b, and c functioning in all cells is replacement of the long first 5'-terminal exon (the 1U exon) encoding 21 amino acid residues with a short one encoding 10 amino acids in the isoforms Oct-1L and Oct-1R. Interestingly, attempts to find mature oct-1 mRNA simultaneously containing the 1L and 1U exons were unsuccessful. The parallel synthesis of "ubiquitous" isoforms Oct-1a, b, and c as well as tissue-specific Oct-1L and Oct-1R in lymphocytes and their precursors may be due either to a high demand of these cells for Oct-1 or to selective participation of different Oct-1 isoforms in regulation of the housekeeping genes and genes involved in the B and T cell differentiation and synthesis of imminoglobulins.

[Tissue-specific splicing of 5'-exons of the Oct-1 transcription factor gene]. / Tkanespetsificheskii splaising 5'-ékzonov gena faktora transkriptsii Oct-1.

It has been shown that pro-mRNA of transcription factor Oct-1 undergoes the tissue-specific splicing. The Oct-1L subform is synthesized in mouse lymphoid myeloma cells NS/0 of the B series and is not found in other somatic and embryonal cells. Initiation sites of oct-1R mRNA transcription are at positions -159 and -307 from the AUG codon of the oct-1R exon. In both cases, no TATA box was found in the region preceding these sites (25-30 bp). A different form of oct-1 mRNA (oct-1U) was also found in NS/0 cells, which is probably synthesized in all cell lines. This subform differs from oct-1R, in particular, by the structure of the 5T-terminal exon, which is the result of alternative splicing.

[Immunoelectrophoresis analysis of the antigenic composition of E. coli K12 hybrids which acquired the serological specificity of S. newcastle and S. flexneri]. / Immunoélektroforeticheskii analiz antigennogo sostava gibridov E. coli K12, priobretshikh serologicheskuiu spetsifichnost' S. newcastle i s. flexneri.

Genetic and immunoelectrophoretic studies confirm earlier data on the presence of 2 specific antigens of acidic nature in S. newcastle; one of them is a specific thermolabile K-antigen responsible for type IV specificity of these bacteria. The data concerning the differences in the genetic determinants controlling the synthesis of O- and K-antigens in S. newcastle have been obtained. S. newcastle O- and K-antigens did not react with S. flexneri in the group serum system 3, 4, which indicates that S. newcastle are serologically isolated and form a separate taxonomic group of dysentery bacteria. The existence of cross reactions between S. flexneri and S. newcastle due to the presence of neutral R-core antigens common to these 2 species has been shown . Immunoelectrophoresis in agar is the most promising and informative method in genetic and chemical studies of the antigenic structure of bacteria.