Objective Grb2-associated binder (Gab) docking proteins have crucialroles in neural development.However, the roles of Gab proteins in the development of synapses remain elusive.Here, we investigate the role of Gab in the development of synapses using the neuromuscular junction as a model of synapse.Methods We generated muscle-specific Gabl mutant but Gab2 null mice by using a loxP/Cre strategy since Gabl null mutation cause embryonic lethality.The Gab 1 (floxed/floxed) Gab2 null mice were crossed with mice expressing the Cre gene under the control of the human skeletal alpha-actin (HSA) promoter.The interaction between Gabl/2 and postsynaptic proteins were identified by co-immunoprecipition assay and Western Blot analysis.And the morphology analysis of the conditional knockout mutation mice was investigated by Immuno-histochemistry and Immuno-fluorescence.Results The conditional knockout (CKO) mice were viable and fertile.The AChR clusters colocalized with markers of presynaptic and postsynaptic markers.However, in comparison with age-matched littermates, the CKO micehave shown the decrease in the AChR cluster area and diameter at postnatal day 1.Conclusion Gab proteins may contribute to the early development of post-synapses of neuromuscular junction.