Fig. 3. Characterization and expression analysis of human nesprin-2. (A) Northern blot analysis of nesprin-2 expression in human tissues. Major transcripts at 11.1 kb, 3.4 kb and 2.7 kb are indicated. The ß-actin loading control is shown. (B) RT-PCR of human nesprin-2 gene expression in aorta indicated that the larger 2 transcript was present in these cells. (C) Gene structure of human nesprin-2. Nesprin 2 comprises 11 exons (55-65), nesprin-2ß is initiated in exon 49, which contains only 5' UTR and comprises 16 exons (excluding exon 56). Nesprin-2 comprises 63 exons (excluding exons 49 and 56). Alternatively spliced exons using cryptic splice sites are shown as open boxes. Alternate splicing at these sites produces transcripts 2₂ and 2ß₂. (D) The deduced amino acid sequence of human nesprin-2, -2ß and -2. The first methionines of nesprin-2, -2ß and -2 are shown in bold and underlined. The 23 residues encoded by exon 56 and specific to nesprin-2 are shown in bold. The open triangle shows the insertion site for 14 residues exclusive to 2₂ and encoded by exon 61 spliced at a cryptic splice site (hatched box in 3C). The spectrin repeats (SR) are shown by numbered grey boxes, the open box indicates the TM region and the dashed open box indicates NLS. GenBank accession numbers for human nesprin-2, -2ß and -2 are AY061758, AY061757 and AY061759, respectively.