The present invention provides recombinant host cells that produce proteins or therapeutic proteins, and nucleic acid constructs for producing the cells. The cells have nucleic acid constructs that encode a heterologous protein, for example an antibody. The nucleic acid constructs also can have a functional signal sequence that directs the secretion of the protein from the cell. The signal sequence can be any functional signal sequence, and various signal sequences are disclosed herein. The invention also provides methods of producing the proteins.