I am looking for results of site-directed mutagenesis experiments in model organisms. Specifically, I want to find non-synonymous mutations that are known to either alter protein function, or to cause no change in function - neutral mutations. The Protein Mutant Database seems to be a good source for this data, but hasn't been updated since 2007.
I've also been looking around the individual model organism databases like FlyBase, WormBase, etc., but it's been very difficult to find neutral mutations (given, it's hard to prove a mutation is truly completely neutral). Are there any other good databases with this sort of data? Thanks.