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comments: The 3'end of CG34339-RB transcript (hereafter nicknamed SOSIE), which encodes a 153 AA polypeptide whose function is currently unknown, shares substantial similarity with 850 nucleotides from genomic DNA near the 3'end of roX1, in addition to similarity with many copies of a satellite repeat present at sites from the middle of the X chromosome. As I reported before, several copies are found near the 5' and 3' ends of the six Rab GTPase paralogs RabX2, Rab9D, Rab9Db, Rab9E, Rab9Fa and Rab9Fb, and of Hmr, as well as in two introns of CG34104 (a gene involved in small GTPase mediated signal transduction). Interestingly, amino acids 49 to 103 of the SOSIE polypeptide exhibit weak similarity with polypeptides encoded by the above six Rab GTPase paralogs. Segments of the satellite repeats also share some degree of homology with 1.688g/cm3 satellite DNA. The CG34339 gene appears to have evolved quite abruptly with the emergence of the melanogaster subgroup species, along with the massive spread of the above X-linked satellite repeats. Although the coding part of CG34339 is relatively well conserved across species of this subgroup, considerable divergence is observed at the 3' ends of all orthologs, which encode proteins of markedly different lengths. By considering that CG34339 transcript has many doubles both in D. melanogaster and in its sibling species, I propose to refer to this transcript as SOSIE.