Minimal Rossmann-like motif (RLM) definition. (A) RLM SSEs adapted from 5-formly-3-hydroxy-2-methylpyridine 4-carboxylic acid (FHMPC) 5-dehydrogenase (PDB: 4OM8) are numbered and colored in rainbow, with magenta catalytic loop between first β-strand—element I (β1) and first α-helix—element II (α1). The second α-helix—element IV (α2) forms crossover between second β-strand—element III (β2) and third β-strand —element V (β3). The crossover loop is unstructured loop at the N-terminal part of α2. Element IV can be α-helix, β-strand, or loop. The unlabeledn SSEs (colored in slate) are considered as an insertion to the RLM, which can occur between element III (β2) and element IV (α2) or in any of the loops connecting the RLM SSEs. (B) An interaction matrix defines RLM search strategy using ProSMoS program. (C) RLM scheme with average AL2CO positional conservation index among family level representatives. RLM bins are colored according to conservation index from blue (not conserved) to red (highly conserved), non-RLM elements are shown in gray. Left side of all SSE corresponds to N-terminus, right side to the C-terminus.