MOLECULAR-CLONING AND CHARACTERIZATION OF ANNEXIN V-BINDING PROTEINS WITH HIGHLY HYDROPHILIC PEPTIDE STRUCTURE

We previously reported that annexin V promoted the survival of culture d rat neocortical neurons. In an effort to elucidate the mechanism und erlying this neurotrophic activity of annexin V, we have attempted to identify the target or binding proteins of annexin V in neuronal cells . Herein, we screened an embryonic day 17 rat brain cDNA library by we stern blot using glutathione S-transferase-annexin V fusion protein as a probe and then isolated four clones showing binding to annexin V in a Ca2+- and phospholipid-dependent manner. Although these cDNAs encod ed different polypeptides, all four polypeptides shared the unique fea ture of containing highly hydrophilic stretches with high Lys, Glu, an d Ser contents. Deduced amino acid sequences of two clones showed high homology with human X-linked Helicase2 (XH2) and DNA (cytosine-5) met hyltransferase (DMTase) sequences, whereas the other two were not rela ted to any known peptide sequence, These results suggest that XH2 and DMTase are candidates for annexin V-binding proteins and thus may medi ate the biological activity of annexin V.