A pyridoxal-phosphate protein. This enzyme is unable to decarboxylate the?D-isomer of threonine?O-3-phosphate. The product of this reaction, (R)-1-aminopropan-2-yl phosphate, is the substrate of EC?6.3.1.10, 5′-deoxyadenosylcobinamide phosphate synthase, which converts adenosylcobyric acid into adenosylcobinamide phosphate in the anaerobic cobalamin biosynthesis pathway.