Meiotic recombination in eukaryotic cells requires two homologs of E. coli RecA protein, Rad51 and Dmc1. Until recently, the role of Dmc1 in meiotic recombination was mostly attributed to genetic studies as purified Dmc1 was found to be a much weaker recombinase than Rad51 in the test tube. Now, Sehorn and colleagues1 have reported that, like Rad51, human Dmc1 is an efficient recombinase in vitro. Dmc1 forms helical nucleoprotein filaments—the signature of classical recombinases such as Rad51. These observations reveal a (...) high level of similitude between the Dmc1 and the Rad51 family of recombination enzymes in higher eukaryotes. BioEssays 26:1151–1155, 2004. © 2004 Wiley Periodicals, Inc. (shrink)