Donor and acceptor splice signals within an exon of the human fibronectin gene: a new type of differential splicing.

We have sequenced that area of a human fibronectin gene clone which codes for a connecting strand separating the last two areas of the type III homology. The gene has a complex exon with two 'AG' acceptor sites. One of these can be used (exon subdivision). In addition 93 basepairs inside the exon are sometimes spliced out as an intron. This is the third differential splicing found in the fibronectin gene transcript and it represents a new type of differential splicing.