RNA recognition motif (RRM) found in activator of basal transcription 1 (ABT1) and similar proteins
This subfamily corresponds to the RRM of novel nuclear proteins termed ABT1 and its homologous counterpart, pre-rRNA-processing protein ESF2 (eighteen S factor 2), from yeast. ABT1 associates with the TATA-binding protein (TBP) and enhances basal transcription activity of class II promoters. Meanwhile, ABT1 could be a transcription cofactor that can bind to DNA in a sequence-independent manner. The yeast ABT1 homolog, ESF2, is a component of 90S preribosomes and 5' ETS-based RNPs. It is previously identified as a putative partner of the TATA-element binding protein. However, it is primarily localized to the nucleolus and physically associates with pre-rRNA processing factors. ESF2 may play a role in ribosome biogenesis. It is required for normal pre-rRNA processing, as well as for SSU processome assembly and function. Both ABT1 and ESF2 contain an RNA recognition motif (RRM), also termed RBD (RNA binding domain) or RNP (ribonucleoprotein domain).