Expression and secretion system

An isolated nucleic acid molecule encoding a first polypeptide, a second polypeptide, a signal sequence, and a coat protein or adaptor protein, wherein:

• (a) the first polypeptide comprises a variable light chain (VL) domain comprising a VL-HVR1, a VL-HVR2, and a VL-HVR3;
• (b) the second polypeptide comprises a variable heavy chain (VH) domain comprising a VH-HVR1, a VH-HVR2, and a VH-VHR3;
• (c) the signal sequence is functional in both a prokaryotic cell and an eukaryotic cell and is encoded by a nucleic acid sequence that is 5′ to the nucleic acid sequence encoding the first polypeptide and 5′ to the nucleic acid sequence encoding the second polypeptide, wherein the signal sequence is encoded by a nucleic acid sequence selected from the group consisting of SEQ ID NO:
• 11 (consensus mBIP sequence, X ATG AAN TTN ACN GTN GTN GCN GCN GCN CTN CTN CTN CTN GGN GCN GTN CGN GCN, wherein N=A, T, C or G, and wherein X =ATG, X=ATG ACC or X is absent), SEQ ID NO:
• 16 (Opt1, ATG ATG AAA TTT ACC GTT GTT GCT GCT GCT CTG CTA CTT CTT GGA GCG GTC CGC GCA), SEQ ID NO:
• 17 (Opt2, ATG ATG AAA TTT ACT GTT GTT GCG GCT GCT CTT CTC CTT CTT GGA GCG GTC CGC GCA), or SEQ ID NO:
• 18 (Opt 3, ATG ATG AAA TTT ACT GTT GTC GCT GCT GCT CTT CTA CTT CTT GGA GCG GTC CGC GCA);
• and
• (d) the first polypeptide and the second polypeptide form a full-length antibody wherein the first and/or second polypeptide is fused to a coat protein or an adaptor protein.