Calmodulin is not the
only protein that senses calicum levels inside and outside the cell. In
fact, before calmodulin was discovered, a protein called TROPONIN C was
found as the first protein to sense varying calcium levels. Once
troponin C senses a certain calcium level, it triggers muscle
contraction. Interestingly, troponin C and calmodulin have very similar
structures. The difference between these two proteins is the length
of the linker conncecting the two
calium-binding domains. However, the actual calcium-binding region is
identical.
Figure 1: A picture of calmodulin (orange) and troponin C (aqua). The red balls represent the 4 calcium molecules bonded
to calmodulin. One can see that the difference between these two proteins is visible at the N-terminus while
the C-terminus of both proteins are identical.
Figure 1: A picture of calmodulin (orange) and troponin C (aqua). The red balls represent the 4 calcium molecules bonded
to calmodulin. One can see that the difference between these two proteins is visible at the N-terminus while
the C-terminus of both proteins are identical.