A synaptic localization domain in the synaptic cleft protein laminin beta 2 (s-laminin)
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.
Martin
P T
PT
Department of Anatomy and Neurobiology, Washington University School of Medicine, St.Louis, MO 63110, USA.
Ettinger
A J
AJ
Sanes
J R
JR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001485:Basement Membrane / Q000737:chemistry / Q000378:metabolism; D002460:Cell Line; D007797:Laminin / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry* / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D009469:Neuromuscular Junction / Q000737:chemistry / Q000378:metabolism; D009842:Oligopeptides / Q000378:metabolism; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011950:Receptors, Cholinergic / Q000032:analysis; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000378:metabolism; D013569:Synapses / Q000737:chemistry / Q000378:metabolism*; D014162:Transfection
D007797:Laminin; D009842:Oligopeptides; D011950:Receptors, Cholinergic; D011993:Recombinant Fusion Proteins; C058783:laminin beta2