Figure 1.

Generation of syntrophin transgenic mice. A, The protein domains of syntrophin are depicted in the four constructs used to generate transgenic mice. FL is the full-length α-syntrophin transgene. The first pleckstrin homology (PH) domain of syntrophin is naturally split by the PDZ domain into PH1a and PH1b. To generate the ΔPDZ transgene the PDZ domain was replaced by a hemagglutinin epitope tag (HA). In the ΔPH1a and ΔPH1b constructs, the 1a and 1b portions of the first PH domain were replaced by Flag and HA epitope tags, respectively. SU refers to the syntrophin unique region. B, Western blot analysis shows the relative expression levels of α-syntrophin in muscle isolated from the transgenic mice. Note the reduced size of syntrophins missing domains. WT, Wild type; KO, α-syntrophin knock-out. C, Immunofluorescence of NMJs in transverse sections of quadriceps muscle. Fluorescent α-bungarotoxin (red) was used to label the postsynaptic acetylcholine receptors. α-Syntrophin is labeled in green. The ΔPH1b sample (and wild-type control) was labeled using the HA antibody since the α-syntrophin-specific antibody epitope is absent in this construct. Scale bar, 10 μm.