Botulinum toxin D ADP-ribosylates a 22-24 KDa membrane protein in platelets and HL-60 cells that is distinct from p21N-ras

Botulinum toxin D ADP-ribosylates a 22-24 KDa protein in platelets, GH3 and HL-60 cells, and a mouse T-cell line CTLL. In platelet homogenates the protein is localized to the membrane fraction, and ADP-ribosylation can also be produced in saponin-permeabilized and intact cells. In the latter, the toxin also potentiates secretion caused by a variety of agonists. In platelets and HL-60 cells the toxin substrate is shown, by use of anti-ras monoclonal antibody, to be distinct from the ras family of proteins. This toxin substrate may represent an additional class of proteins involved in stimulus-response coupling.