The absence of substitutions, or the presence of only very conservative substitutions (that is, the substitution of amino acids whose side chains have similar biochemical properties) in a particular region of the sequence, suggest that this region has structural or functional importance.
Odsustvo supstitucija, ili prisustvo samo veoma konzerviranih supstitucija (drugim rečima, supstitucija aminokiselina čiji bočni lanci imaju slične biohemijske osobine) u određenom regionu sekvence, sugeriše da taj region ima strukturni ili funkcionalni značaj.