Intramembrane-cleaving aspartic protease (I-CLiP) that cleaves type II membrane signal peptides in the hydrophobic plane of the membrane. Catalyzes intramembrane proteolysis of some signal peptides after they have been cleaved from a preprotein, resulting in the release of the fragment from the ER membrane into the cytoplasm. Ubiquitous. Strongly expressed in vegetative shoot apex, young panicle, developing panicle, and the early developing florets. The first transmembrane domain may act as a type I signal anchor. The PAL motif is required for normal active site conformation. Belongs to the peptidase A22B family.