The PNKKPRL sequence is conserved and functional in insect Cabut orthologs.

<p>(A) Multiple alignment of Cbt proteins from <i>Drosophila</i> species and other insects, showing that the PNKKPRL motif is highly conserved. A consensus sequence for the putative NLS is shown below (X = any amino acid). (B–D) Localization of β-Gal fusion proteins in <i>Spodoptera exigua</i> Sec301 cells transiently transfected with the constructs shown in (A). Cells were stained with anti-β-Gal (red; first panel) and anti-Lam (green; second panel) to mark nuclear membranes. The overlay panel depicts double staining of cells with both antibodies, and the localization of the fusion proteins is shown in the fourth panel (C, cytoplasmic; N, nuclear). Note that all β-Gal fusion proteins containing the wild-type PNKKPRL sequence were translocated to the nucleus. Scale bar: 10 µm. (E) Western blots of protein extracts from Sec301 cells transfected with constructs shown in (A) and stained with anti-β-Gal. (1) Non-transfected Sec301 cells, (2) pIE-β-Gal-Cbt_1–428 (∼160 kDa), (3) pIE-β-Gal-Cbt_1–77 (∼135 kDa) and (4) pIE-β-Gal-Cbt_{1–K73N–K74N} (∼135 kDa).