PMID: 25962468

Authors:

Moran T, Gat Y, Fass D

Title:

Laminin L4 Domain Structure Resembles Adhesion Modules in Ephrin Receptor and Other Transmembrane Glycoproteins.

Journal:

FEBS J. 2015 May 11. doi: 10.1111/febs.13319.

Abstract:

The ~800 kD laminin heterotrimer forms a distinctive cross-shaped structure that further self-assembles into networks within the extracellular matrix (ECM). The domains at the laminin chain termini, which engage in network formation and cell-surface interaction, are well understood both structurally and functionally. In contrast, the structures and roles of additional domains embedded within the limbs of the laminin cross have remained obscure. Here we report the X-ray crystal structure, determined to 1.2 A resolution, of the human laminin alpha2 subunit L4b domain, site of an in-frame deletion mutation associated with mild congenital muscular dystrophy. The alpha2 L4b domain is an irregular beta-sandwich with many short and broken strands linked by extended loops. The most similar known structures are the carbohydrate-binding domains of bacterial cellulases, the ephrin binding domain of ephrin receptors, and MAM adhesion domains in various other eukaryotic cell-surface proteins. This similarity to mammalian adhesion modules, which was not predicted on the basis of amino acid sequence alone due to lack of detectable homology, suggests that laminin internal domains evolved from a progenitor adhesion molecule and may retain a role in cell adhesion in the context of the laminin trimer. This article is protected by copyright. All rights reserved.