RNA Exonuclease 1 Homolog (REXO1)

REXO1 bound directly to TCEB3 and to the N terminus of the transcription elongation factor SII (TCEA1), which is homologous to the N terminus of TCEB3. Immunofluorescence on COS-7 cells showed REXO1 and TCEB3 colocalized within the nucleus. REXO1 did not affect either the rate of transcription elongation by RNA polymerase II or the transcriptional activity of TCEB3 in vitro.The elongin heterotrimeric protein complex increases the rate of transcription elongation by suppressing the pausing of RNA polymerase II along the DNA template. The 1,221-amino acid REXO1 protein has a predicted molecular mass of 131.5 kD and contains an exonuclease domain at the C terminus. Northern blot analysis showed ubiquitous expression of a 4.4-kb transcript.