Fig. 4. Collagen invasion is mediated by nuclear CapG. (A) Amino acid sequence alignment between the N-termini of fragminP, severin and CapG; aa 1-27 mark the severin/fragminP nuclear export sequence. Shaded residues are conserved. Residues marked in black are hydrophobic. (B) Nuclear CapG promotes collagen invasion (upper panel). Fusion of the FrgP NES to CapG-EGFP blocks collagen invasion (lane 3, `control'). Mutation of FrgP I9 or I14 to alanine shows no effect on collagen invasion (lanes 4-5). Mutation of L17, L21 or L27 to alanine restores nuclear localization and collagen invasion (lanes 6-8). Lower panel: western blot showing equal expression of the fusion proteins.