This study identifies key ATP-binding residues in the N and P domains of the sarcoplasmic reticulum Ca2+-ATPase and highlights the crucial role of Mg2+ in modulating nucleotide-protein interactions.
Does not support clinical SERCA targeting; leaves open whether these residues modulate cardiac calcium handling in vivo.
ATP-binding residues in the N and P domains of sarcoplasmic reticulum Ca-ATPase have been investigated using mutagenesis in combination with a binding assay based on the photolabeling of Lys(492) with [g-(32)P] 2',3'-O-(2,4,6 trinitrophenyl)-8-azido-ATP and competition with nucleotide. In the N domain, mutations to several residues in conserved motifs, (438)GEATE, (487)FSRDRK, (515)KGAPE, and (560)RCLALA produce nucleotide-binding defects. Key residues include Thr(441), Glu(442), Phe(487), Arg(489), Lys(492), Lys(515), Arg(560), and Leu(562). In the absence of Mg(2+), Arg(489), Lys(492), and Arg(560) are most important, whereas in its presence Thr(441) and Glu(442) also play a crucial role. In the P domain, Asp(351) is striking for its strong electrostatic repulsion of the gamma-phosphate, especially in the presence of Mg(2+). Lys(352) is a key residue, and Asp(627) and Lys(684) must come close to the nucleotide. Thr(353), Asn(359), Asp(601), and Asp(703) interact only in the presence of Mg(2+). Asn(706) and Asp(707) are unimportant for nucleotide binding. The results identify several ATP binding residues in the N and P domains and suggest that Mg(2+) changes the nucleotide/protein interaction in both. Models of bound ATP and MgATP are presented.
No takes yet. Share an insight, caveat, or question.
McIntosh et al. (2003) studied this question.
Synapse has enriched 5 closely related papers on similar clinical questions. Consider them for comparative context: