Evidence for an interaction of paracingulin with microtubules.

The mechanisms that anchor microtubules to epithelial junctions are poorly understood. Here we show that recombinant purified paracingulin ( CGNL1 , JACOP), a cytoplasmic junctional protein, decorates microtubules by negative staining electron microscopy and co-pellets with microtubules. Co-pelleting experiments using fragments of CGNL1 indicate that this is mediated by a central region of the CGNL1 head domain (residues 250-420). Deletion of a basic amino-acid stretch (365-377) within this fragment, abolishes both co-pelleting with and decoration of microtubules. These results suggest that paracingulin can interact directly with microtubules through a basic amino-acid stretch of its head domain.