Fig. 1. Calmodulin binding to myosin VIIa. (A) Diagram of the primary structure of native myosin VIIa, indicating the motor domain (head), the five IQ motifs (and potentially bound light chains (grey ellipses)), the coiled-coil domain (CC) and the tail, which includes the Myth4 and FERM domains (Chen et al., 1996; Weil et al., 1996). (B) Sequences of the five IQ motifs of human myosin VIIa (Hasson et al., 1995) compared with the IQ consensus motif. The number of asterisks indicates the extent of similarity of each motif to the consensus motif. Mouse myosin VIIa differs from the human at the following amino acids: N to H in IQ2; first Q to E and T to A in IQ4 (Mburu et al., 1997). (C) Immunoprecipitation of myosin VIIa and calmodulin from bovine retina with myosin VIIa antibodies. Preimmune serum (control Ab) and the N-terminal myosin VIIa antibody fail to immunoprecipitate myosin VIIa or calmodulin (lanes 1 and 2), whereas the tail myosin VIIa antibody immunoprecipitates both. (D) Release of calmodulin from immunoprecipitate. The beads containing the immunprecipitate (lane 1) were washed with buffer containing 1 mM EGTA (lane 2) or 10 µM Ca2+ (lane 3). More calmodulin is released in the presence of Ca2+, and this calmodulin characteristically has a slightly higher mobility in SDS-PAGE.
