Absence of wild-type FGF1 in S10 cortex. (a) Predicted amino-acid sequence of FGF1 protein from SR1 and S10 hippocampus reveals a putative truncation of the S10 protein sequence at the carboxy terminus. The reference FGF1 protein sequence is shown at the top. The site of the 15-bp insertion is indicated by an arrow and the resulting amino-acid changes and the truncation predicted in S10 FGF1 are highlighted in yellow. The nuclear localization signal (NLS), the FGF core domain and the heparin-binding motif are indicated by boxes. (b) A western blot of S8, S10 and SR1 cortices probed with an antibody specific for the carboxy terminus of FGF1 is shown. This region is predicted to be deleted in S10 mice. Wild-type mouse FGF1 is 155 amino acids and 17.4 kD. As predicted, wild-type FGF1 is detected in the cortices of S8 and SR1, but not S10, consistent with the predicted truncation of the protein in that strain of mice.