respectively). Alternative splicing is thought to be possible due to two polyadenylation sites, one appearing between the Cu and C?, and the other 3' of C? (polyadenylation in the latter site would cause Cu to be spliced away along with the intron). The precise mechanism of how the polyadenylation site is chosen remains unclear.

The resulting functional mRNA will have the V-D-J and C regions contiguous, and its translation will generate either