MauL is one of the products from the methylamine utilization gene cluster in Methylobacterium extorquens AM1. Mutants generated by insertions in mauL were not able to grow on methylamine or any other primary amine as carbon sources. MauL belongs to the blue or type I copper protein family. They are involved in electron transfer reactions with the Cu center transitioning between the oxidized Cu(II) form and the reduced Cu(I) form.