Reports

A synaptic localization domain in the synaptic cleft protein laminin beta 2 (s-laminin)

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Science  21 Jul 1995:
Vol. 269, Issue 5222, pp. 413-416
DOI: 10.1126/science.7618109

Abstract

The basal lamina that ensheaths skeletal muscle fibers traverses the synaptic cleft at the neuromuscular junction. Synaptic and extrasynaptic portions of the basal lamina contain different laminin beta chains: beta 2 (or s) at synapses and beta 1 (or B1) extrasynaptically. Laminin beta 2 is also confined to synapselike patches on myotube surfaces in vitro, whereas beta 1 is present throughout the extracellular matrix. This differential localization of laminin beta chains was analyzed by expression of chimeric beta 1-beta 2 molecules in cultured mouse myotubes. A 16-amino acid carboxyl-terminal sequence in beta 2 was necessary for synaptic localization, and an amino-terminal domain in beta 1 promoted association with extracellular fibrils. The synaptic targeting sequence of beta 2 contains a site previously shown to be adhesive for motor neurons.