ELL2, A NEW MEMBER OF AN ELL FAMILY OF RNA-POLYMERASE-II ELONGATION-FACTORS

We recently isolated an RNA polymerase II elongation factor from rat l iver nuclei and found it to be homologous to the product of the human ELL gene, a frequent target for translocations in acute myeloid leukem ia. To further our understanding of the possible role(s) of ELL in tra nscriptional regulation and human disease, we initiated a search for E LL-related proteins. In this report we describe molecular cloning, exp ression, and characterization of human ELL2, a novel RNA polymerase II elongation factor 49% identical and 66% similar to ELL. Mechanistic s tudies indicate that ELL2 and ELL possess similar transcriptional acti vities. Structure-function studies localize the ELL2 elongation activa tion domain to an ELL2 N-terminal region that is highly homologous to ELL. Finally, Northern blot analysis reveals that the ELL2 and ELL gen es are transcribed in many of the same tissues, but that the ratio of their transcripts exhibits tissue-to-tissue variation, raising the pos sibility that ELL2 and ELL may not perform completely general function s, but, instead, may perform gene- or tissue-specific functions.