Ctr1 is like the entrance of a hotel.
We at CopperOne think that any copper in the cuprous, Cu+, oxidation state is best because entering through the specific Ctr1 channel is like entering a hotel through the front door. Once you enter, you have a bell hop and concierge to help you find your way to your room and make sure that electron you’ve got in your outer valence shell doesn’t go where it shouldn’t. Like O2!!!
DMT1 is like a side door
We at CopperOne call the +2 oxidation state Cu2+ “toxic copper.” Well, it is better than nothing if one is a cow or goat eating copper deficient vegetable matter and made more copper deficient with molybdenum. (For a very technical post, follow this link.) We hear stories of humans taking mega doses of copper sulfate. Why??? Sure, it can enter through the divalent metal cotransporter (DMT1) side door. Why should some of the other divalent minerals that our bodies need have to stand in line?
Sure, Cu2+ entering through the DMT1 side door will eventually get reduced to Cu+ via glutathione or something. Not that this is speculation waiting to be experimentally verified. It will make its way to its room, we hope. It just seems profoundly ill advised to take mega doses of any form of Cu2+… to us anyway.
It should be noted that both Cu+ and Cu2+ can bind to the transcription factor Sp1 to shut down the expression of Ctr1.