Synaptonemal Complex Proteins: Unicity or Universality?

The preparatory pairing of homologous chromosomes is the obligatory step of meiosis. It occurs through formation of synaptonemal complexes (SC): the protein axes of two chromosomes are connected with the help of additional “central space proteins.” These proteins are sometimes species-specific and serve as the object of comparative studies. With the help of bioinformatics methods, we studied proteins structuring the SC central space in animals and fungi. We established that Ecm11 and Gmc2 had a low level of conservation even within the taxon of Ascomycetes. The SIX6OS1 protein of the mouse, as well as SYCE1–SYCE3 and TEX12 in animals, was moderately conserved only within the subphylum of vertebrates, despite these proteins (with the exception of SYCE3) occurring in invertebrates too. Thus, we have confirmed the thesis that, in addition to the common set of meiotic proteins, every evolutionary line of Eukaryotes has developed its own proteins for the formation of SC, the general structure of which is common between all eukaryotes.