Further evidence for a common mechanism for shedding of cell surface proteins

Pro-TNF alpha Steel factor, type II IL-1R and II-2R alpha were expressed in COS-7 cells and the generation of their soluble forms was examined, The release of all four proteins was strongly stimulated by the phorbol ester PMA and completely blocked by a hydroxamate-based inhibitor of metalloproteases, COS-7 cell membranes were found to cleave various synthetic pro-TNF alpha peptides with the same specificity as a partially purified TNF alpha converting enzyme purified from human monocytic cells, suggesting that the same enzyme may be responsible for at least some of the COS-7 cell shedding activity.