Background

Because of the importance of cholesterol, all animal cells are able to synthesize it. The cholesterol biosynthesis starts with the cataluzed conversion of Acetyl-CoA into HMG-CoA.

Your Mission

Complete the first step of the cholesterol biosynthesis pathway, the conversion of Acetyl-CoA to HMG-CoA, catalyzed by HMGCS1. The complete reaction is depicted in this figure:



  • Download the starter pathway here: met-1-first-start.gpml.
  • Launch PathVisio and open the dowloaded file via File > Open. The two metabolites, Acetyl-CoA and HMG-CoA, and the conversion between them have already been added. You will be adding the enzyme and the catalysis interaction.

      • Add the enzyme

    • Select GeneProduct from the Data Node palette in the Objects tab.
    • Click on the canvas to place the node.
    • Double-click on the node to open its properties.
    • Search for “HMGCS1”. Choose any of the entries that represents an exact match for “HMGCS1”, and choose the identifier from either HGNC, Ensembl or Entrez (in that order of priority).
    • To select an identifier, click once to highlight the row in the results list, and then click OK. Alternatively, double-click on the row.
    • Click OK again to close the node properties window.

      • Add and connect the catalysis arrow

    • Select the mim-catalysis arrow from the MIM interactions palette in the Objects tab.
    • Drag and drop anywhere on the canvas to create the interaction.
    • Drag the plain end (start) of the interaction over a target area on the enzyme node (highlighted in green on hover).
    • Drag the catalysis end (end) of the interaction over the anchor (small dot) on the conversion line.
    • (Optional) Align nodes using toolbar actions.
    • Done!
  • Save your work as a GPML file under File > Save As.
  • Drag-and-drop the GPML file below to to check if it is correct.