Unknown

Dataset Information

0

Ca2+ release to lumen from ADP-sensitive phosphoenzyme E1PCa2 without bound K+ of sarcoplasmic reticulum Ca2+-ATPase.


ABSTRACT: During Ca(2+) transport by sarcoplasmic reticulum Ca(2+)-ATPase, the conformation change of ADP-sensitive phosphoenzyme (E1PCa(2)) to ADP-insensitive phosphoenzyme (E2PCa(2)) is followed by rapid Ca(2+) release into the lumen. Here, we find that in the absence of K(+), Ca(2+) release occurs considerably faster than E1PCa(2) to E2PCa(2) conformation change. Therefore, the lumenal Ca(2+) release pathway is open to some extent in the K(+)-free E1PCa(2) structure. The Ca(2+) affinity of this E1P is as high as that of the unphosphorylated ATPase (E1), indicating the Ca(2+) binding sites are not disrupted. Thus, bound K(+) stabilizes the E1PCa(2) structure with occluded Ca(2+), keeping the Ca(2+) pathway to the lumen closed. We found previously (Yamasaki, K., Wang, G., Daiho, T., Danko, S., and Suzuki, H. (2008) J. Biol. Chem. 283, 29144-29155) that the K(+) bound in E2P reduces the Ca(2+) affinity essential for achieving the high physiological Ca(2+) gradient and to fully open the lumenal Ca(2+) gate for rapid Ca(2+) release (E2PCa(2) ? E2P + 2Ca(2+)). These findings show that bound K(+) is critical for stabilizing both E1PCa(2) and E2P structures, thereby contributing to the structural changes that efficiently couple phosphoenzyme processing and Ca(2+) handling.

SUBMITTER: Yamasaki K 

PROVIDER: S-EPMC2992300 | biostudies-literature | 2010 Dec

REPOSITORIES: biostudies-literature

altmetric image

Publications

Ca2+ release to lumen from ADP-sensitive phosphoenzyme E1PCa2 without bound K+ of sarcoplasmic reticulum Ca2+-ATPase.

Yamasaki Kazuo K   Daiho Takashi T   Danko Stefania S   Suzuki Hiroshi H  

The Journal of biological chemistry 20101011 49


During Ca(2+) transport by sarcoplasmic reticulum Ca(2+)-ATPase, the conformation change of ADP-sensitive phosphoenzyme (E1PCa(2)) to ADP-insensitive phosphoenzyme (E2PCa(2)) is followed by rapid Ca(2+) release into the lumen. Here, we find that in the absence of K(+), Ca(2+) release occurs considerably faster than E1PCa(2) to E2PCa(2) conformation change. Therefore, the lumenal Ca(2+) release pathway is open to some extent in the K(+)-free E1PCa(2) structure. The Ca(2+) affinity of this E1P is  ...[more]

Similar Datasets

| S-EPMC2662013 | biostudies-literature
| S-EPMC4646029 | biostudies-literature
| S-EPMC7961605 | biostudies-literature
| S-EPMC5724008 | biostudies-literature
| S-EPMC3624456 | biostudies-literature
| S-EPMC2025671 | biostudies-literature
| S-EPMC2679452 | biostudies-literature
| S-EPMC2157260 | biostudies-literature
| S-EPMC2755681 | biostudies-literature
| S-EPMC1150156 | biostudies-other