Members of the TCP family of transcription factors have so far only been found in plants, where they are implicated in processes related to cell proliferation. It appears that TCP domain (see <PDOC51369>) protein have been recruited during evolution to control cell division and growth in various developmental processes. The TCP proteins fall into two subfamilies, one including CYC and TB1 and the other including the PCFs. Most members of the CYC/TB1 subfamily have an R domain, predicted to form a coiled coil that may mediate protein-protein interactions [1,2].

The R domain is rich in polar residues (arginine, lysine and glutamic acid) and is predicted to form a hydrophilic α-helix [1].

Some proteins known to contain a R domain are listed below:

• Antirrhinum majus cycloidea (CYC). It is involved in the control of floral symmetry, a character that has changed many times during plant evolution.
• Maize teosinte branched 1 (TB1). It controls developmental switches that contributed to the evolution of maize from its wild ancestor teosinte.
• Arabidopsis thaliana TCP2 and TCP3, which correlate with actively dividing regions of the floral meristem.

The profile we developed covers the entire R domain.