Overview of mutations introduced into syb-2 in the present investigation. All targeted sites are layer residues facing the inside of the complex (Fasshauer et al., 1998) either at the N-terminal end (left) or at the C-terminal end (right) of the complex. In the LATA mutant, aa 32 (leucine) and aa 35 (threonine) corresponding to layers −7 and −6 were mutated to alanine. The VAVA mutant bears mutations in layers −5 and −4, where valines (residues 39 and 42) were mutated to alanines. In the C-terminal half of the complex, leucine-70 was mutated to alanine (L70A) and phenylalanine was mutated to alanine (F77A) in layers 4 and 6, respectively. In layer 8, leucine was substituted by alanine (L84A), arginine (L84N), glycine (L84G), or aspartate (L84D).