S100A1: A Regulator of Striated Muscle Sarcoplasmic Reticulum Ca²⁺ Handling, Sarcomeric, and Mitochondrial Function

Figure 2

The three-dimensional structure of S100A1 as determined by NMR spectroscopy. (a) S100A1 in the apo state: S100A1 is composed of two identical subunits connected by a linker region (hinge region). Dimerization occurs in an antiparallel manner. (b) S100A1 in the Ca²⁺ bound state: Ca²⁺ binding to both the N- and C-terminal motif results in an altered orientation of H3/4 and the hinge region uncovering hydrophobic residues for the interaction with target molecules. S100A1 residues 75–94 are indicated by the red box. Reproduced with modifications from Wright et al. [7].

(a)

(b)