Mg2+‐ATP induces filament growth from retinal rod outer segments with disrupted plasma membranes

Mg2+‐ATP produces a large decrease in near‐IR light scattering when added to suspensions of rod outer segments (ROS) when the plasma membranes have been disrupted by a gentle dialysis procedure. When this process is studied by light microscopy with video‐enhanced image contrast, the Mg2+‐ATP‐dependent signal is seen to be associated with the formation of filaments which extend only from those ROS lacking plasma membranes. Both the IR light scattering signal and filament growth are inhibited by vanadate and DCCD but not by colchicine, colcemid or cytochalasins.