Fig. 1. Complexin 1 (CPX I) is highly expressed in insulin-secreting cells. (a) Total RNA (15 µg) from different tissues were prepared and were subjected to northern blot analysis as described previously (Abderrahmani et al., 2001). RNAs were hybridized with a full-length rat cDNA CPX I probe that shares more than 80% sequence homology with CPX II (Takahashi et al., 1995). A transcript of 2.3 kb corresponding to CPX I is abundantly detected in the brain (used as a positive control for CPXs expression) and in three insulin-secreting cell lines (INS1, ßTC3 and MIN6 cells). A band of 5 kb corresponding to CPX II mRNA, is observed in the brain, in HeLa and RAW and at low levels in ßTC3 cells (Takahashi et al., 1995; McMahon et al., 1995). CPX II was not detected in INS1 and MIN6 cells. (b) Western blot analysis performed with total protein extracts from insulin-secreting cell lines and pancreatic islets confirmed expression of CPXs protein.