<p>Type I protein secretion is a system in some Gram-negative bacteria to export proteins (often proteases) across both inner and outer membranes to the extracellular medium. This is one of three proteins of the type I secretion apparatus. Targeted proteins are not cleaved at the N terminus, but rather carry signals located toward the extreme C terminus to direct type I secretion.</p> ATPase, type I secretion system, PrtD