PROSITE documentation PDOC51022

L27 domain profile

The L27 domain is a ~50-amino acid module, initially identified in the Lin-2 and Lin-7 proteins, that exists in a large family of animal scaffold proteins [1]. The L27 domain is a specific protein-protein interaction module capable of forming heteromeric complexes that can integrate multiple scaffold proteins into supramolecular assemblies required for establishment and maintenance of cell polarity. The L27 domain can be found as a single occurrence or as a duplication in association with other domains such as PDZ (see <PDOC50106>), SH3 (see <PDOC50002>), the guanylate kinase domain (see <PDOC00670>) or the serine/threonine protein kinase domain (see <PDOC00100>).

The main features of the L27 domain are conserved negatively charged residues and a conserved aromatic amino acid [1]. Study of individual L27 domains revealed largely unfolded domains that require the formation of obligate heterodimers to achieve well-folded structures. Each L27 domain is composed of three helices. The two L27 domains heterodimerize by building a compact structure consisting of a four-helix bundle formed by the first two helices of each L27 domain and one coiled-coil formed by the third helix of each domain (see <PDB:1RSO>) [2,3].

Some proteins known to contain a L27 domain are listed below:

• Members of a subset of membrane-associated guanylate kinases (MAGUKs).
• Lin-7-like proteins.

The profile we developed covers the entire L27 domain.