(A) Schematic representation of wild type SYT (WT SYT; 1–387 aa) and its mutants including the SYT functional domains QPGY and SNH. (B) 3D collagen cultures of MDCK cells expressing Flag/HA- tagged pOZ vector, WT SYT, SYTdl 1–40, SYTdl 8 and SYT 1–164NLS. NT: not-transfected. (C) Data analysis of the relative number and size of MDCK cysts expressing the various SYT-derived cDNAs. Large is >250 μm diameter, Medium is 150–250 μm diameter and Small is <150 μm in diameter. The data shown are representative of four independent experiments (n=4). (D) Infection efficiency of the pOZ retroviral transduction system. MDCK cells were infected with FLAG/HA tagged pOZ retroviral vector expressing WT SYT, SYTdl 1–40, SYTdl 8 and SYT 1–164NLS. HA- specific antibody was used for visualization of the expressed proteins. The cytoplasmic HA staining in pOZ vector infected cells is due to the generation of an irrelevant FLAG/HA-tagged peptide by the vector. Magnification 20X. (E) Expression levels of the pOZ proteins in MDCK cells visualized with the Flag antibody. The protein band in the pOZ vector lane is the irrelevant vector-generated polypeptide that disappears upon subcloning of SYT cDNAs.