E1A Binding Protein P400 (EP400)

Sequence analysis of the p400 band by ion trap mass spectrometry resulted in the identification of 5 peptides that all mapped to a partial cDNA clone (CAGH32) identified by Margolis et al. (1997) in a screen for cDNAs with long CAG trinucleotide repeats. Fuchs et al. (2001) obtained a full-length cDNA encoding p400 by cDNA library screening, RACE, and homology alignment with fragments of the mouse homolog. The predicted 3,124-residue p400 protein contains the distinct signature motifs that constitute the DNA-dependent ATPase/helicase-like domain of SWI2/SNF2 family members. An unusual feature of this domain is the presence of an approximately 500-residue linker sequence separating it into 2 subsegments. RT-PCR and in situ hybridization analyses showed that p400 is ubiquitously expressed.