Skeletal muscle syntrophin interactors revealed by yeast two-hybrid assay

Syntrophins are the cytoplasmic peripheral proteins of dystrophin glycoprotein complex, of which five (alpha l, beta 1, beta 2, gamma 1 and gamma 2) isoforms have been identified so far. Respective syntrophin isoforms are encoded by different genes but have similar domain structures. At the sarcolemma of skeletal muscle, the most abundant alpha l-syntrophin was shown to interact at its PDZ domain with many membrane proteins. Among them, the AQP4 interaction with alpha 1-syntrophin PDZ domain was demonstrated by a Tg mouse study, prompting us to investigate the interaction between mouse alpha l-syntrophin (BC018546: nt.267-492, PDZ domain) pEXP-AD502 as prey vector and mouse AQP4 (NM009700: nt.805-969) pDBLeu as bait vector by the yeast two-hybrid assay, resulting in a negative study. We further studied the binding partner of another sarcolemma located beta 1-syntrophin, and performed a yeast two-hybrid experiment. With human beta 1-syntrophin as bait and human skeletal muscle cDNA library as prey, we obtained one positive clone which turned out to be alpha-dystrobrevin. Although the interaction of human beta 1-syntrophin with alpha-dystrobrevin has already been shown by immunoprecipitation assay, we have here confirmed this interaction by a yeast two-hybrid experiment.