Peflin, a novel member of the five-EF-hand-protein family, is similar to the apoptosis-linked gene 2 (ALG-2) protein but possesses nonapeptide repeats in the N-terminal hydrophobic region

The calpain small subunits of sorcin, grancalcin, and ALG-2 constitute a fa mily of the Ca2+-binding proteins with five EF-hand-like motifs (penita-EF- hand domain or PEF domain) in their C-terminal regions and hydrophobic doma ins with variable lengths in their N-terminal regions. Searching the human DNA data base of expressed sequence tags (EST) revealed novel partial seque nces similar to, but distinct from, the sequences of the previously known P EF proteins. We isolated a cDNA clone of near full length by 5'- and 3'-RAC E (rapid amplification of cDNA end) methods and compared the predicted amin o acid sequence (284 residues) of the novel EF-hand protein, named peflin, with those of known PEF proteins. The PEF domain of peflin is most similar to ALG-2 (40.9% identity) among the family, particularly in EF-1 (46.2%) an d EF-3 (57.1%) regions. Peflin has a longer N-terminal hydrophobic domain t han any other member of the family, and it contains nine nonapeptide (A/PPG GPYGGP) repeats; Western blot analysis demonstrated that peflin (30 kDa) wa s expressed in various nonadherent and adherent cultured human cell lines, including Jurkat, HL60, HeLa, and HT1080. Peflin may play basic roles in Ca 2+ signaling irrespective of cell types. (C) 1999 Academic Press.