Review Article
The Calcium-Dependent Interaction of S100B with Its Protein Targets
Table 1
Dissociation of Ca2+ and Mn2+ from the EF-hand calcium-binding domains in wild-type and mutant S100 proteins.
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| The value listed is from previously published papers [109, 113], so direct comparisons of binding constants using similar methods/conditions could be made ( target, Figure 3). Several others report binding constants using different methods and varying conditions for EF1 (200 M 500 M) and for EF2 (10 M 60 M) [58, 78, 86, 87, 114–120]. The dissociation rate constant for wild-type S100B was determined via stopped-flow methods and is 60 22 s-1. The off-rate together with the enables the calculation of a macroscopic on-rate value of 1.1 106 M-1 s-1 that includes calcium-association plus a large conformational change. The value for the mutants was also determined using competition studies of Ca2+ with the respective Tb3+-bound S100B mutant in the absence and presence of p53 peptide. The dissociation constants together with the calcium off-rate values measured for the E31A and E72A mutants of 7.1 3.7 s-1 and 6.8 2.0 s-1, respectively, were sufficient to calculate on-rate values of 3.4 2.0 106 M-1 s-1 and 3.7 1.3 106 M-1 s-1 for the mutants [109, 113]. From Charpentier et al. (2010) [34]. From Wright et al. (2005) [61]. From Wright et al. (2009) [59]. S100A1 has also been shown to bind the full-length ryanodine receptor at 100 nM free Ca2+ [60, 67]. From Franz et al. (1998) [89]. From Fritz et al. (1998). A tenfold weaker affinity was reported when purified under aerobic conditions [90, 121]. From Dukhanina et al. (1998). A weaker affinity was reported under different conditions in Pedrocchi et al. (1994) when S100A4 was originally discovered [122, 123]. From Schäfer et al. (2000). For a direct comparison of Ca2+ and Zn2+ binding to S100A5 to those of other S100 proteins (i.e., S100B, S100A2, S100A3, S100A4, S1006, and S10011), under identical conditions and Methods, also see Schäfer et al., (2000) [124]. From Kuznicki and Filipek (1987) and Mani and Kay (1990). Kordowska et al. also measured Ca2+-binding for S100A6 under different conditions (~18 M) and found that binding to the target caldesmon (CaD) increased the affinity of S100A6 for Ca2+ by approximately 6-fold [96, 125, 126]. Other measurements under higher salt and other varying conditions are also reported with weaker affinities for S100A6 [68, 124]. From Schäfer et al. (2000) [124]. Weaker binding to Ca2+ has also been reported for this protein in other conditions [127]. No data is available for S100A8/A9, and S100A10 does not bind Ca2+. From Allen et al. (1996) and Schäfer et al., (2000) [124, 128]. Note the affinity for Ca2+ increases by 10-fold upon the addition of a target molecule as found with other S100 proteins [128]. From Dell’Angelica et al. (1994). Note that Zn2+-binding to S100A12 significantly increases Ca2+-binding affinity for this protein in the presence of Zn2+ (EF2: = 40 nM, EF1: = 15 M) [129]. From Ridinger et al. (2000). This protein is unique among S100 family members in that it does not bind to the hydrophobic binding dye, TNS, upon the addition of Ca2+ [130]. No data is yet available for S100A14, and there is no S10015 [131]. From Sturchler et al. (2006). The value in the table is for human S100A16, mouse S100A16 bound one calcium too, only weaker ( = 0.75 mM) [132]. From Becker et al. (1992) and Gribenko et al., (1998) [92, 133]. In Gribenko et al., (1998), the effects of Mg2+ binding on Ca2+ affinity are also rigorously addressed. | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||