Mutational Analysis of Putative Calcium Binding Motifs within the Skeletal Ryanodine Receptor Isoform, RyR1

The EF-hand Ca2+ Binding Domain Is Not Required for Cytosolic Ca2+ Activation of the Cardiac Ryanodine Receptor

“…Ca 2ϩ binding studies have shown that these two EF-hands bind Ca 2ϩ with millimolar affinities, suggesting that they may be involved in Ca 2ϩ -dependent inactivation of the channel because single RyR channels are inactivated by millimolar Ca 2ϩ (8). Consistent with this view, Fessenden et al (10) have also found that mutating the EF1 sequence reduced the sensitivity of RyR1 to Ca 2ϩ -dependent inactivation ϳ2-fold but increased the sensitivity of RyR1 to Ca 2ϩ -dependent activation ϳ2-fold. Interestingly, mutating the EF2 sequence abolished high-affinity [ 3 H]ryanodine binding, but single EF2 mutant channels remained sensitive to cytosolic Ca 2ϩ activation.…”

“…p Ͻ 0.05 was considered to be statistically significant. (8,10). The sequences of EF1 and EF2 in RyRs share a high degree of homology with that of the C-lobe of CaM (Fig.…”

Structural Determinants of 4-Chloro-m-cresol Required for Activation of Ryanodine Receptor Type 1

“…This segment is directly adjacent to the Gln 4020 Lys 4021 dipeptide that is critical for activation of RyR1 by 4-CmC (Fessenden et al, 2006). In addition, this segment contains the putative "Ca 2ϩ sensor" at residue Glu 4032 (Chen et al, 1998) and also is in proximity to EF hand motifs implicated in Ca 2ϩ regulation of RyR1 activity (Xiong et al, 1998(Xiong et al, , 2006Fessenden et al, 2004) (Fig. 9).…”

How to open a Ryanodine Receptor

“…Wei et al point to an EF-hand region as the prime suspect, as it was reported before that mutations in this area have an effect on Ca 2+ sensitivity [10]. A more recent study showed that deletion of the entire EF-hand domain did not affect Ca 2+ -dependent activation of RyR2, suggesting that the EF-hand is not the primary Ca 2+ sensor [11].…”