2. Dystrophin is a large protein with
molecular mass of 427,000 Da.
It connects the thin filaments(actin-
filaments) to the transmembrane protein
beta-dystroglycan in the sarcolemma by
smaller proteins called syntrophins.
3. Beta –dystroglycan is connected to
merosin in the extracellular matrix by
alpha-dystroglycan.
Merosin refers to laminins that contain
the alpha2 sub-unit .
The Dystroglycans are in turn associated
with a complex of 4 transmembrane
glycoproteins : alpha,beta,gamma and
delta –sarcoglycan.
4. The dystrophin-glycoprotein complex
adds strength to the muscle by providing
a scaffolding for the fibrils and
connecting them to extracellular matrix.
5. Complete absence of dystrophin causes
Duchenne muscular dystrophy.It is fatal
by the age of 30yrs.
Altered or reduced amount of dystrophin
causes Becker muscular dystrophy.