1HN, 13C, and 15N resonance assignments of human calmodulin bound to a peptide derived from the STRA6 vitamin A transporter (CaMBP2)
Vitamin A is a necessary nutrient for all mammals, and it is required for the transcription of many genes and vital for vision. While fasting, the vitamin A alcohol form (Retinol) from storage in the liver is mobilized and transported through the bloodstream while bound to retinol binding protein (RBP). Details of how exactly vitamin A is released from RBP and taken into the cells are still unclear. As part of the effort to elucidate the specifics of this process, single-particle cryo-electron microscopy structural studies of STRA6 (the RBP receptor 75-kDa transmembrane receptor protein) were recently reported by Chen et al. (Science, https://doi.org/10.1126/science.aad8266, 2016). Interestingly, STRA6 from zebrafish was shown to be a stable dimer and bound to calmodulin (CaM), forming a 180-kDa complex. The topology of the STRA6 complex includes 18 transmembrane helices (nine per protomer) and two long horizontal intramembrane helices interacting at the dimer core (Chen et al., in Science, https://doi.org/10.1126/science.aad8266, 2016). CaM was shown to interact with three regions of STRA6, termed CaMBP1, CaMBP2, and CaMBP3, with the most extensive interactions involving CaMBP2. To further our understanding of Ca2+-dependence of CaM-STRA6 complex formation, studies of the structure and dynamic properties of the CaMBP2–CaM complex were initiated. For this, the 1HN, 13C, and 15N backbone resonance assignments of the 148 amino acid Ca2+-bound calmodulin protein bound to the 27-residue CaMBP2 peptide derived from STRA6 were completed here using heteronuclear multidimensional NMR spectroscopy.
KeywordsVitamin A Retinoic acid Calmodulin STRA6
This work is supported by 1R01EY027405 (F.M.) and shared instrumentation grants to the UMB NMR center from the National Institutes of Health [S10 RR10441, S10 RR15741, S10 RR16812, and S10 RR23447 (D.J.W.)] and from the National Science Foundation (DBI 1005795 to D.J.W.). This work was also supported via the Center for Biomolecular Therapeutics (CBT) at the University of Maryland.
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Conflict of interest
The authors declare that they have no conflict of interest.
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