Palindromic sequences are associated with sites of DNA breakage during gene conversion.

Gene conversion is a recombinatorial mechanism which transfers genetic information from a donor into a recipient gene. A case of gene conversion between immunoglobulin VH region genes was analysed and palindromic sequences were found to be located near to the left recombinatorial breakpoint, which also is flanked by a direct repeat sequence. We performed a computer search for palindromes and direct repeats in the published sequences of eucaryotic genes which had been involved in gene conversion. In these sequences, the palindrome with the best or second best quality is located near to a breakpoint of recombination. A correlation of recombination breakpoints with direct repeats was not observed. This suggests that gene conversion is promoted by palindromic sequences

Structural and functional properties of ribosomal protein L7 from humans and rodents.

By subtractive screening of a library made from mRNA of lipopolysaccharide (LPS)-stimulated mouse B lymphocytes we isolated cDNA-clones encoding the ribosomal protein L7. Human L7 mRNA was cloned from activated T-lymphocytes. Although no specific function of L7 in the translation apparatus is known as yet, it should be a critical one as indicated by its high degree of structural conservation during evolution and its regulated expression in lymphoid cells. Human and rodent L7 proteins carry sequences similar to the basic-region-leucine-zipper(BZIP)-motif of DNA-binding eucaryotic transcription factors. We show here that the region of L7 carrying the latter motif mediates L7-dimerization and stable binding to DNA and RNA. A preferential binding to RNA-structures is demonstrated