cDNA cloning using expression library

[Takahiko Ito]

When you screen random primed expression library using yeast 
two-hybrid system or antibody binding, what is the easiest 
way to know the obtained partial cDNA is encoding the sense 
(mRNA)strand of a certain gene? In other words, when you get 
a new sequence which does not have any homology to known 
genes, how and when can you tell the protein sequence you 
predict by sequencing the insert does exist in the cell?