Figure 1. Sequence comparison of the kinase domain of Arabidopsis LYK proteins. Schematic representation shows the kinase domain of AtCERK1 (drawn to scale). Kinase subdomain I and VIb to VIII are selectively highlighted below the drawing to highlight the five AtLYK proteins. Identical and similar residues throughout the alignment are shown in black and gray, respectively. The consensus line among the eukaryotic protein kinase superfamily⁴⁷ is given according to the following code: uppercase letters, invariant residues; o, conserved nonpolar residues; +, conserved small residues with near neutral polarity. Note that AtCERK1 and AtLYK3 have an intact intracellular kinase domain.