Go
to the main content page
Striated
muscle. Proteins of the myofilaments
To
understand the finer structural details of the myofilaments
and the mechanism by which sliding, and ultimately muscle
contraction, is brought about one must turn to the molecular
components of the filaments and of the structures associated
with them. The myofilaments are composed of several different
proteins, constituting about 50 percent of the total protein
in muscle. The other 50 percent consists of the proteins
in the Z line and M band, the enzymes in the sarcoplasm
and mitochondria, collagen, and the proteins in membrane
structures. Of the myofilament proteins, myosin and actin
are known to play a direct part in the contractile event.
Troponin and tropomyosin, which are located in the thin
filaments together with calcium ions, regulate contraction
by controlling the interaction of myosin and actin.
