Fig. 1. Dp71-associated protein complex. The Dp71DAPC is a multiprotein complex that connects the cytoskeleton to the plasma membrane of non-muscular cells. Dp71 has an actin-binding site at its N-terminal region (NH₂). It forms a bridge between the actin cytoskeleton and the transmembrane protein ß-dystroglycan (ß-DG). ß-dystroglycan interacts with Dp71, utrophin and actin via its cytoplasmic tail. Moreover, defects in ß-dystroglycan are central to the pathogenesis of structural and functional neural abnormalities observed in DMD. On the cytoplasmic side of the complex, Dp71 binds to syntrophins (Syn) and dystrobrevins. Syntrophins are a family of five proteins (, ß1, ß2, 1 and 2) containing two pleckstrin homology domains and a PDZ domain. The PDZ sequence serves as an adaptor for the recruitment of syntrophin-associated proteins (SAPs) such as: ion and water channels, receptors, kinases and neural nitric oxide synthase (nNOS). -Syntrophin is the main isoform found in sperm. The localization of - and ß-dystrobrevins was unrelated to Dp71DAPC localization in guinea pig spermatozoa (Hernández-González et al., 2001), thus we propose that they are components of flagellar structures. Like Dp71, Up71 is able to bind ß-dystroglycan, syntrophins and F-actin. Therefore, it could compensate for Dp71 absence in mdx^3cv spermatozoa, forming a Up71DAPC with -syntrophin.