The activity of m-calpain, a heterodimeric, Ca 2+ -dependent cysteine protease appears to be modulated by membrane interactions involving oblique-orientated a-helix formation by a segment, GTAMRILGGVI, in the protein’s smaller subunit. Here, graphical and hydrophobic moment-based analyses predicted that this segment may form ana-helix with strong structural resemblance to the influenza virus peptide, HA2, a known oblique-orientateda-helix former.