Transcriptional termination sequences in the mouse serum albumin gene.

Poly(A) signals are required for efficient 3' end formation and transcriptional termination of most protein-encoding genes transcribed by RNA polymerase II. However, transcription can extend far beyond the poly(A) site before termination occurs. This implies the existence of further downstream termination signals. In mammals, a variety of sequence elements, in addition to the poly(A) site, have been implicated in the termination process. For example, termination of the human beta- and epsilon-globin genes is mediated by a sequence downstream of the poly(A) site that promotes an RNA cotranscriptional cleavage (CoTC). Here we report the identification of multiple termination sequences in the mouse serum albumin (MSA) 3' flanking region. Many transcripts from this region are cleaved cotranscriptionally, implying that such cleavage of pre-mRNA may be a more general feature of transcriptional termination.