Fig. 5. CUP interacts with TIC. (A) The interaction between CUP and TIC, first detected in a yeast two-hybrid screen, was confirmed by GST pulldown. The lanes labelled CUP and TIC contain in vitro synthesised, radiolabelled CUP and TIC protein controls, respectively. The lanes labelled CUP^* and TIC^* contain the pulldown products resulting from combining labelled CUP or TIC with GST-fusion proteins with CUP (CUP^G) or TIC (TIC^G) or GST alone. The strong band in the CUP^*TIC^G lane corresponds to an interaction between labelled CUP and GST-TIC. A weaker band in the TIC^*CUP^G lane shows the interaction between labelled TIC and GST-CUP. A band is also observed in the TIC^*TIC^G lane, indicating that TIC also interacts with itself. (B) The tissue specific expression of TIC and CUP was investigated by RT-PCR (35 cycles) using RNA derived from leaf (L), inflorescence (I), sepal (Se), petal (P), stamen (St) and carpel (C) tissues. The expression pattern of CUP is as expected from in situ hybridisation experiments, being absent from mature leaves, sepals and stamens, and present in carpels and petals. The strongest expression is detected in inflorescences, where in situ hybridisation shows that CUP is expressed at the many boundaries between developing meristems and primordia. The expression pattern of TIC broadly follows that of CUP, but shows a wider tissue distribution. Equal loading is shown by an elongation factor control.