Fig. 2.
1t→2 tandems fail to generate functional channels. A, The presumed membrane orientation of the NR1t→2 tandem. The TM4 tail for NR1, the subunit truncated to form the tandem, is included as a separate subunit. The symbol above indicates the order of subunits in the tandem, with thetruncated subunit missing a 90οsegment forming the start or head of the tandem (NR1, white). NR2, black. B, NR1t→2 tandems do not generate currents. Currents from NR1 and NR2A cells (Control) recorded on the same day as NR1t→2 tandems alone, or with different full-length subunits added, are shown. The NR1t→2 tandem gives no significant currents alone or with any combination of single subunits. Diagrams of tandems are included in the histograms to indicate which DNAs were introduced to the cells for each column. Data are given in Table2.