FEATURES OF THE STRUCTURE OF THE 7K VARIA NT OF THE DROSOPHILA-MELANOGASTER GYPSY RETROTRANSPOSON SUGGEST THAT 7K-COPIES ARE CAPABLE OF AUTONOMOUS TRANSPOSITION

The complete nucleotide sequence of the 7K variant of the gypsy retrot ransposon of Drosophila melanogaster was determined. This variant belo ngs to the 7K subfamily of gypsy, which was previously considered inac tive. All differences found in the sequenced 7K copy compared to the t ranspositionally active 6K variants were point mutations. These nucleo tide substitutions account for about 1% of the total base pair number of gypsy, Long terminal repeats (LTR) have the highest rate of nucleot ide substitutions However, changes in nontranslated regions did not in volve the promoter region and other supposed cis-acting elements. Sixt een amino acid substitutions were found in the coding region of gypsy, These substitutions were mainly located on the boarders of potential functional domains and within the third open reading frame (ORF3). Com parative analysis of structures of these two variants of gypsy suggest s the potential ability of 7K copies to transpose.