Fig. 4.

Alternative splicing of basonuclin 2 gene. The accession numbers of the various mouse and human mRNAs found in GenBank are given. The asterisk indicates an error in the sequence of HSM806660 reported in GenBank. An adenine between nucleotides 1254 and 1255 is missing; this adenine is found on BAC AL449983. The primary transcript can be spliced in different ways (introns are designated with Roman numerals) and translated into different proteins, some of which lack all or some of the zinc fingers (thick vertical bars in the protein). Regions of proteins shared with basonuclin 2 (NM_172870) are shaded, whereas regions that differ are cross-hatched. UTRs are empty. Dashed lines show that some protein sequences are incomplete because they are deduced from partial-length cDNAs. AK031440 contains two additional exons (1a and 2a). Exon 1a encodes the putative initiating methionine; exon 2a is in frame with exons 2 and 4. The AK031440 coding region terminates within intron IV. AK000050, AK025882, and BC037160 are similar to NM_172870. AK092247 contains two additional small exons (5a and 5b) at its 3′ end and terminates within exon 5a. It therefore lacks zinc fingers 4–6. HSM806660 uses a poly(A) addition site located 2 kb downstream from that used by the other human transcripts. It encodes the usual protein. Slashes indicate that exon 6 of HSM806660 is not drawn to scale.