Intramembrane proteolysis by signal peptidepeptidases - a comparative discussion of GxGD-type aspartyl proteases
J Biol Chem. 2009 May 22;284(21):13975-9. Epub 2009 Feb 3.
Intramembrane-cleaving proteases are required for reverse signaling and membrane
protein degradation. A major class of these proteases is represented by the
GXGD-type aspartyl proteases. GXGD describes a novel signature sequence that
distinguishes these proteases from conventional aspartyl proteases. Members of
the family of the GXGD-type aspartyl proteases are the Alzheimer disease-related
gamma-secretase, the signal peptide peptidases and their homologs, and the
bacterial type IV prepilin peptidases. We will describe the major biochemical and
functional properties of the signal peptide peptidases and their relatives. We
then compare these properties with those of gamma-secretase and discuss common
mechanisms but also point out a number of substantial differences.