EAL domain. This domain is found in diverse bacterial signaling proteins. It is called EAL after its conserved residues and is also known as domain of unknown function 2 (DUF2). The EAL domain has been shown to stimulate degradation of a second messenger, cyclic di-GMP, and is a good candidate for a diguanylate phosphodiesterase function. Together with the GGDEF domain, EAL might be involved in regulating cell surface adhesiveness in bacteria.