The CAMTA family of calmodulin binding transcription factors comprises six members in Arabidopsis (Bouche et al., 2002; Finkler et al., 2007). Each protein includes an IQ domain for calmodulin binding; ankyrin repeats for protein interactions; the TIG domain, which has nonspecific DNA binding activity; and the CG-1 domain, which has specific DNA binding activity. The CG-1 domain recognizes the core consensus sequence, vCGCGb, referred to as the CG-1 element (da Costa e Silva, 1994). This sequence matches the CM2 sequence, CCGCGT, and overlaps the ICEr1 element. Thus, the possibility was raised that one or more of the CAMTA proteins might have a role in regulating CBF2 expression.
