2.9.1.2 tetramer a member of the Fold Type I pyridoxal 5'-phosphate enzyme family, forms an (alpha2)2 homotetramer through its N-terminal extension. The active site lies on the dimer interface with each monomer contributing essential residues 694428 2.9.1.2 tetramer two SepSecS monomers form a homodimer, and two active sites are formed at the dimer interface. The two homodimers associate into a tetramer through interactions between the N-terminal alpha1-loop-alpha2 motifs 695136 2.9.1.2 homotetramer - -, 738683 2.9.1.2 homotetramer 4 * 60000, recombinant enzyme, SDS-PAGE 762417