For functional characterization of predicted genes encoding hypothetical proteins in fungal genomes, it is complementary to genetic studies to determine their expression and subcellular localization patterns in different developmental or infection stages. It is also important to identify and characterize other proteins that are physically associated with or functionally related to these genes in vivo by co-immunoprecipitation or affinity purification analyses. In this chapter, we described a set of yeast shuttle vectors and protocols to generate fusion constructs by the yeast gap repair approach. Because of the simplicity and efficiency of yeast gap repair, these vectors and the general methods described in this chapter are suitable for functional genomics studies in filamentous fungi.