Structures of EF-hand Ca
-binding proteins. (A) Domain structures of Ciona and Chlamydomonas Ca2+-sensors, drawn based on SMART searches (http://smart.embl-heidelberg.de/). The length of each protein and the positions of EF hand motifs are scaled below. (B) Molecular models of ligand-unbound Ciona centrin and NCS-1, built using SWISS-MODEL (http://swissmodel.expasy.org) . Templates used are 1tnx.1 (skeletal muscle troponin) and 2d8n.1 (human recoverin) for Ciona centrin and NCS-1, respectively.