Fig. 4

Splice site analyses using NetGene2 and ASSP, revealed that in the presence of the insertion, in addition to the correct splice-site occurring at the exon- intron boundary, a further two splice sites are present in the insertion (a). These alternate splicing events result in a frameshift mutation, which results in a premature stop codon at amino acid 421, indicated by the arrow (b). Grey shading indicated the 12 transmembrane regions of the sialin protein