Physiologically Relevant Free Ca²⁺ Ion Concentrations Regulate STRA6-Calmodulin Complex Formation via the BP2 Region of STRA6.

ABSTRACT: The interaction of calmodulin (CaM) with the receptor for retinol uptake, STRA6, involves an α-helix termed BP2 that is located on the intracellular side of this homodimeric transporter (Chen et al., 2016 [1]). In the absence of Ca²⁺, NMR data showed that a peptide derived from BP2 bound to the C-terminal lobe (C-lobe) of Mg²⁺-bound CaM (^MgCaM). Upon titration of Ca²⁺ into ^MgCaM-BP2, NMR chemical shift perturbations (CSPs) were observed for residues in the C-lobe, including those in the EF-hand Ca²⁺-binding domains, EF3 and EF4 (^CaK_D = 60 ± 7 nM). As higher concentrations of free Ca²⁺ were achieved, CSPs occurred for residues in the N-terminal lobe (N-lobe) including those in EF1 and EF2 (

SUBMITTER: Young BD 

PROVIDER: S-EPMC8568335 | biostudies-literature | 2021 Nov

REPOSITORIES: biostudies-literature