Four pairs of alpha-helices each form independent 12-amino-acid loops containing a negatively charged calcium binding domain known as an EF-hand. However, only three of these EF hands are functional (the most N-terminal EF-hand does not bind calcium).
Four sets of alpha-helices create separate 12-amino-acid segments with a negatively charged calcium-binding region called an EF-hand. However, only three of these EF hands are functional (the most N-terminal EF-hand does not bind calcium).