Download MendeleyStructural Basis for the Differential Effects of CaBP1 and Calmodulin on Ca(V)1.2 Calcium-Dependent Inactivation.
Findeisen, F., Minor, D.L.(2010) Structure 18: 1617-1631
- PubMed: 21134641
- DOI: https://doi.org/10.1016/j.str.2010.09.012
- Primary Citation of Related Structures:
3OX5, 3OX6 - PubMed Abstract:
Calcium-binding protein 1 (CaBP1), a calmodulin (CaM) homolog, endows certain voltage-gated calcium channels (Ca(V)s) with unusual properties. CaBP1 inhibits Ca(V)1.2 calcium-dependent inactivation (CDI) and introduces calcium-dependent facilitation (CDF). Here, we show that the ability of CaBP1 to inhibit Ca(V)1.2 CDI and induce CDF arises from interaction between the CaBP1 N-lobe and interlobe linker residue Glu94. Unlike CaM, where functional EF hands are essential for channel modulation, CDI inhibition does not require functional CaBP1 EF hands. Furthermore, CaBP1-mediated CDF has different molecular requirements than CaM-mediated CDF. Overall, the data show that CaBP1 comprises two structural modules having separate functions: similar to CaM, the CaBP1 C-lobe serves as a high-affinity anchor that binds the Ca(V)1.2 IQ domain at a site that overlaps with the Ca²+/CaM C-lobe site, whereas the N-lobe/linker module houses the elements required for channel modulation. Discovery of this division provides the framework for understanding how CaBP1 regulates Ca(V)s.
Organizational Affiliation:
Cardiovascular Research Institute, University of California, San Francisco, CA 94158-2330, USA.
