[Localization in the body of the mobile element MDG1 of 2 regions specifically binding with Drosophila nuclear proteins]. / Lokalizatsiia v tele mobil'nogo élementa MDG1 dvukh zon, spetsificheski sviazyvaiushchikhsia s iadernymi belkami drozofily.

Two regions in mdg1 mobile element's body can specifically bind nuclear proteins of Drosophila melanogaster, as demonstrated by the method of retention of DNA-protein complexes of nitrocellulose filters. The first region is situated in the 5'-end part of mdg1, 1 kb downstream the site of initiation of transcription and contains long oligo (A) blocks (from 14 to 30 nucleotides) in the coding chain. The second region is localized near the 3'-LTR and consists of tandem 14-nucleotide repeats and a palindrome, destruction of which leads to weaker binding. There is no competition between the two regions for proteins, which evidence that they are recognized by the different proteins. The binding with the first region can be suppressed by adding the 412 mobile element DNA. These regions are supposed to take place in the regulation of mdg1 transcription.

[Interaction of products of su(Hw) and su(f) genes with MDG4 region regulating its transcription suppresses mutations in Drosophila caused by insertion of this gene]. / Vzaimodeistvie produktov genov su(Hw) i su(f) s oblast'iu MDG4, reguliruiushchei ego transkriptsiiu, supressiruet mutatsii u drozofily, vyzvannye vstraivaniem étogo gena.

The mdg4 (gypsy) mobile element of Drosophila contains two closely situated regions binding to proteins from nuclear extracts. One of these is an imperfect palindrome having homology with the lac operator of Escherichia coli, the other contains a reiterated sequence (5'PyPuTCTGCATACTPyPy) homologous to the octamer which is the core of many enhancers and upstream promoter elements. The transient expression of deletion mutants has shown that these DNA regions are negative and positive regulators, respectively, of mdg4 transcription. As was demonstrated earlier, mutations induced by the presence of mdg4 at different loci are suppressed, owing to either repression or activation of mdg4 transcription in Drosophila lines carrying unlinked mutations in su(Hw) or su(f) genes. We have shown that binding to a negative regulator (silencer) is weakened in nuclear extracts isolated from cell lines carrying su(f) mutations which activate mdg4 transcription; therefore, the su(f) gene codes for a protein capable of mdg4 repression. Furthermore, binding to a positive regulator is weakened in nuclear extracts isolated from cell lines carrying su(Hw) gene mutations which decrease the level of mdg4 transcription; hence, the su(Hw) gene encodes a protein which activates mdg4 transcription.