Domain

NtA (N-terminal agrin) domain (IPR004850)

Short name: NtA_dom

Domain relationships

None.

Description

Agrin is a multidomain heparan sulphate proteoglycan, that is a key organiser for the induction of postsynaptic specializations at the neuromuscular junction. Binding of agrin to basement membranes requires the amino terminal (NtA) domain [PMID: 9321698]. This region mediates high affinity interaction with the coiled-coil domain of laminins. The binding of agrin to laminins via the NtA domain is subject to tissue-specific regulation. The NtA domain-containing form of agrin is expressed in non-neuronal cells or in neurons that project to non-neuronal cell such as motor neurons. The NtA domain forms the most N-terminal part, followed by 9 Kazal-like domains and 2 LE domains. The C-terminal part consists of a SEA domain, 4 EGF-like domains and 3 Laminin G domains, responsible for the clustering of acetylcholine receptors [PMID: 11473262].

Tertiairy structures show that the NtA domain folds as a beta-barrel core flanked by N- and C-terminal helical regions. The core of the domain consists of 5 beta-strands that form 2 beta-sheets. The structure belongs to the OB fold family and shows similarity with the protease inhibition domain of TIMP-1, suggesting alternative functions for agrin in addition to synaptogenic activity [PMID: 11473262]. Residues Leu 117 and Val 124 in helix 3 of the NtA domain are essential for binding to the laminin gamma1 chain [PMID: 12554653].

GO terms

Biological Process

GO:0007213 G-protein coupled acetylcholine receptor signaling pathway
GO:0043113 receptor clustering

Molecular Function

GO:0043236 laminin binding

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
Pfam
PROSITE profiles