Despite their recognition as molecular machines, Type I R-M enzymes have often not been viewed as useful molecular motors.  This may reflect the problems associated with DNA cleavage.  As mentioned earlier, these enzymes will cleave DNA once the process of translocation is stopped.  Therefore, anything covalently attached to DNA is liable to produce this situation limiting the uses of the motor as an actuator for moving objects.  However, Janscák et al. (1998) showed that, for the EcoR124I Type I R-M enzyme, there is a sub-assembly species of the holoenzyme (the R1-complex shown in Figure 4), which does not cleave DNA.