Characterisation of a novel minisatellite that provides multiple splice donor sites in an interferon-induced transcript.

Nucleotide sequence features of the human interferon-inducible gene 6-16 are described and include, within a CpG island, a partially expressed minisatellite consisting of 26 tandemly repeated dodecanucleotides. The repeat unit consensus sequence (CAGGTAAGGGTG) is similar to the mammalian splice donor consensus sequence [(A/C)AGGT(A/G)AGT]. The splice donor site of exon 2, as determined previously, forms part of the most upstream of the repeat units. We show that the two neighbouring repeat units also provide functional splice donor sites effectively extending exon 2 by 12 or 24 nt and inserting four or eight amino acids respectively into the predicted gene product. A similar pattern of differently spliced transcripts is detected in several human cell types. Both the number of repeat units per allele and the nucleotide sequence itself show limited polymorphism within the human population. Similar minisatellites from nonhuman primates are described and also appear to modulate splicing of a 6-16 transcript. The 6-16 minisatellite is therefore an example of tandemly repeated DNA that has a role in gene expression and may provide a useful in vivo system for the analysis of 5' splice site choice and minisatellite biology.