InterPro: IPR001791 Laminin G

Laminins are large heterotrimeric glycoproteins involved in basement membrane function [1]. The laminin globular (G) domain can be found in one to several copies in various laminin family members, including a large number of extracellular proteins. The C terminus of the laminin alpha chain contains a tandem repeat of five laminin G domains, which are critical for heparin-binding and cell attachment activity [2]. Laminin alpha4 is distributed in a variety of tissues including peripheral nerves, dorsal root ganglion, skeletal muscle and capillaries; in the neuromuscular junction, it is required for synaptic specialisation [3]. The structure of the laminin-G domain has been predicted to resemble that of pentraxin [4].

Laminin G domains can vary in their function, and a variety of binding functions have been ascribed to different LamG modules. For example, the laminin alpha1 and alpha2 chains each have five C-teminal laminin G domains, where only domains LG4 and LG5 contain binding sites for heparin, sulphatides and the cell surface receptor dystroglycan [2]. Laminin G-containing proteins appear to have a wide variety of roles in cell adhesion, signalling, migration, assembly and differentiation. Proteins with laminin-G domains include:

• Laminin.
• Merosin.
• Agrin.
• Neurexins.
• Vitamin K dependent protein S.
• Sex steroid binding protein SBP/SHBG.
• Drosophila proteins Slit, Crumbs, Fat.
• several proteoglycan precursors.