The glyoxylate bypass allows E. coli to generate precursors for biosynthesis during growth on acetate as the sole carbon source. During growth on acetate, there is competition between isocitrate dehydrogenase (ICDH) and isocitrate lyase (ICL) for the common substrate, isocitrate. Previous studies have shown that ICDH is regulated by reversible phosphorylation during growth on acetate. Although much is known about ICDH, comparatively little is known about the structure or catalytic mechanism and regulation of ICL.