Catalyzes the cleavage of L-allo-threonine and L-threonine to glycine and acetaldehyde. L-threonine = acetaldehyde + glycine L-allo-threonine = acetaldehyde + glycine Amino-acid biosynthesis; glycine biosynthesis; glycine from L-allo-threonine: step 1/1. Amino-acid degradation; L-threonine degradation via aldolase pathway; acetaldehyde and glycine from L-threonine: step 1/1. Homotetramer. Present with 106000 molecules/cell in log phase SD medium. Belongs to the threonine aldolase family.