Polyadenylation of the 3' tail
The hnRNA product
includes a signal sequence (AAUAAA) towards the 3'
end. An enzyme complex cuts off the 3' end, and
another enzyme complex synthesizes a poly-A tract
and attaches it to the free 3' end.
[Note: The molecule
shown is hnRNA, not mRNA, and is cut upstream
of the signal sequence.]
Figure © 2012 TA Brown, Introduction to Genetics (1st ed.); additional text © 2012 by Steven M. Carr