(a) Interactions of dystrophin with dystrophin‐associated glycoprotein complex and signalling molecules (NOS and syntrophins). Dystrophin is a major component of the subsarcolemmal skeleton of muscle cells, and is part of a molecular multinetwork, the DAGC that links the intracellular cytoskeleton to the extracellular matrix. This protein complex, in addition to dystrophin, encompasses intracellular (α1 and β1 syntrophin, α‐dystrobrevin and nNOS), transmembrane (β‐dystroglycan, α‐, β‐, γ‐ and δ‐sarcoglycan, and sarcospan) and extracellular proteins (α‐dystroglycan and laminin‐2). (b) Pathogenic cascade related to the dystrophin absence. Absence of dystrophin leads to instability of the membrane with a pseudo‐wound state; this is accompanied initially by necrosis, hypertrophy of fibres and regenerations (phase I) but it is followed by a progressive loss of regeneration and muscular degeneration/fibrosis characteristic of DMD (phase II). These processes are not only species specific, being very different in humans, mice and dogs, but also age dependent, as in DMD where the lack (or strong reduction) of regeneration occurs during the prepuberty age.
The decipherment of the genetic code was instrumental in elucidating the mechanism of protein biosynthesis, a process that includes the transfer of genetic information contained in the DNA to the molecules of messenger RNA (mRNA). This process, the essence of which is the synthesis of mRNA on the DNA template, is called transcription. Messenger RNA then becomes associated with special cell structures called ribosomes, on which the polypeptide chain is synthesized in accordance with the information contained in the mRNA molecule. This process of the synthesis of polypeptide chains through the mediation of mRNA is called translation.