Molecular dissection of neuromuscular junction formation.

The muscle-specific kinase (MuSK) is the key component that mediates the synapse-inducing role of motoneuron-derived agrin at the neuromuscular junction. Recent reverse-genetics approaches have shed new light on the events triggered inside myotubes by activation of this kinase. Mice in which most of the intracellular domain of MuSK is replaced by a related kinase are viable. Analysis of the imperfect postsynaptic specializations of these mice has provided new insights into the complex postsynaptic differentiation process.