1. A method for producing a diploid yeast cell capable of displaying a multi-chain polypeptide, the method comprising: obtaining a first haploid yeast cell expressing at least a first chain of the multi-chain polypeptide linked to a yeast cell surface anchor protein, obtaining a second haploid yeast cell expressing at least a second chain of the multi-chain polypeptide, contacting the first haploid yeast cell and the second haploid yeast cell under conditions that permit the haploid cells to fuse, thereby producing the diploid yeast cell that is capable of displaying the multi-chain polypeptide on its surface, wherein the first haploid yeast cell and the second haploid yeast cell are of opposite mating type.