Fold and topology of SAM binding proteins. Corresponding fragments of cartoon and topology representations of selected structures were rainbow colored from N-terminal (blue) to C-terminal (red) end. Less significant fragments of secondary structure were left white in topology diagrams. Reference to other representative structures are provided (in parentheses) as SCOP sunid numbers (i.e. ref. ). (a) 1ej0A, Rossmann-fold methyltransferase (53335 excluding: 102555, 69556, 69557, and 69560); (b) 1l1eA, cyclopropane fatty acid synthase (69560); (c) 1mjfA, spermidine synthase (69557); (d) 1vhvA, porphyrin C-methyltransferase (53789); (e) 1j6rB, Met synthase reactivation domain (methyltransferase; 56506); (f) 1mxiA, SPOUT methyltransferase (89629, 75218); (g) 1r30A, SAM dependent radical enzyme (102114); (h) 1mvhA, SET domain methyltransferase (82199); (i) 1rqpB, 5'-fluoro-5'-deoxyadenosine synthase (102521, 101851); (j) 1m7y, 1-aminocyclopropane-1-carboxylate (ACC) synthase (53441, 64130, and similar but different: 53439); (k) 1vkyA, tRNA-ribosyl transferase-isomerase (111338); (l) 1o9tB, methionine adenosyltransferase (55972); (m) 1cmc, MetJ – methionine repressor (dimer; 100972); (n) 1msvA, SAM decarboxylase (56275); (o) 1pbjA, CBS domain (dimer; 54630 – not all CBS domains bind SAM); (p) 1kzfA, acyl-homoserine lactone synthase (75508).