For calcium to be absorbed it must bind to a hormone regulated brush border protein called what

For calcium to be absorbed it must bind to a hormone regulated brush border protein called Calbindin.
Calbindins are calcium binding protein. As it names also shows that, Cal for calcium and bindin for binding. they are also described as vitamin D dependent calbindin proteins.
Calbindin-D9k and Calbindin-D28k are two identified forms of protein. 

Atp is is our little "pocket" of energy. of course, if you have too little, then it means you have too little energy, and you'll pass out. the way to not have enough, is to have no energy sources (glucose, fats, proteins). you can't have too many atp molecules. cycles like the krebs cycle produce it, but if you have too much of any substrate (or too little for that matter), the cycle stops and atp is no longer made (it stops until substrate levels are such that the process can go on). in any case, this is unlikely since atp is constantly hydrolyzed and remade, even while you're asleep. you won't have too much. if you have zero, you are dead or dying.