When this element binds troponin, it opens up spots for myosin to form crossbridges.
Roger Tsien  (tsee-EN)  designed a GFP variant called Cameleon that senses this element. Parvalbumin and other proteins that bind this element have a motif that looks like a hand. In humans, mineralization refers to the binding of this element to phosphates. When this element binds troponin, it opens up spots for myosin to form crossbridges. Protein kinase C signaling is activated by this (*)  secondary messenger, which accumulates in the sarcoplasmic reticulum in cells. Influx of this element at a synapse stimulates acetylcholine release and muscle contraction. All forms of vitamin D are named for this element, levels of which are controlled in the body by parathyroid hormone to activate osteoblasts and osteoclasts. For 10 points, name this metal required for bone formation.
Roger Tsien  (tsee-EN)  designed a GFP variant called Cameleon that senses this element.
calcium  [or  Ca 2+] 