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Troponin is one of the protein molecules that (together
with myosin,
actin,
and tropomyosin)
forms the cylindrical structures called myofibrils that,
together, form muscle
fibers.
Myofibrils consist of two types of protein filaments, called
thin
filaments, and thick
filaments. Troponin molecules, together with
tropomyosin and actin molecules, form the thin filaments which have
a helix structure - as shown in the diagram below.
Above: Diagram of Troponin molecules within a Thin Filament.
Troponin acts in combination with tropomyosin to control
muscle contraction.
During muscle relaxation, troponin holds tropomyosin in position
covering myosin-binding sites on actin proteins. (The protein myosin
is part of the thick filaments of muscle fibers.)
During muscle contraction calciun ions (Ca2+) bind to troponin,
changing the shape of the troponin-tropomyosin complex and therefore
uncovering the myosin-binding sites on the protein action (which is part
of the thick filaments of muscle fibers).
For further detail about troponin, visit St
Vincent's Hospital website .
This Section consists of short summaries about the
structures that form the muscles of the body.
This list is not exhaustive but is intended to be appropriate for students
of A-Level Human Biology, ITEC courses in massage and related subjects,
and some other courses in Health Sciences. Visitors
are encouraged to supplement their study by reading many different sources.
For more general information about Muscles see
the pages about:
Anterior
Muscles, Posterior
Muscles, Facial
Muscles, Terminology
about Muscles, and the Structure
of Muscles. |
