HTT and Huntington disease: We found a change in the relative distribution of wild-type and mutant Huntingtin in a single fraction (fraction 4) but a change in the distribution of five membrane proteins (intrinsic or membrane-associated) in synaptic fractions generated by iodixanol separation of Q175/Q7 HD mice versus Q7/Q7 mouse brain lysates providing evidence to support synaptic changes in the HD mice.