PROS1 and glycogen storage disease VI: The importance of C1 for the Cu+-mediated protein heterocomplexes between the yeast proteins Atx1 and the first Cu+-binding domain of the Ccc2 ATPase27 and, between human Atox1 and MK1 (the first Cu+-binding domain of Menke’s disease protein)21, has been reported previously using NMR experiments probing protein heterocomplex via increased reorientation time of molecular tumbling.