| IPR009029 | Hydroxymethylglutaryl-CoA reductase, class I/II, substrate-binding domain superfamily | Homologous Superfamily |
| IPR023074 | Hydroxymethylglutaryl-CoA reductase, class I/II, catalytic domain superfamily | Homologous Superfamily |
| IPR009023 | Hydroxymethylglutaryl-CoA reductase, class I/II, NAD/NADP-binding domain superfamily | Homologous Superfamily |
| IPR002202 | Hydroxymethylglutaryl-CoA reductase, class I/II | Family |
| IPR004553 | Hydroxymethylglutaryl-CoA reductase, bacterial-type | Family |
| IPR023076 | Hydroxymethylglutaryl-CoA reductase, class I/II, conserved site | Conserved Site |