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1. a delicate fiber or thread.
2. in an x-ray tube, the wire (cathode) that makes electrons available for interaction with the anode when it is heated to incandescence to form an electron cloud.
actin filament one of the thin contractile filaments in a myofibril, composed mainly of actin; each actin filament is surrounded by three myosin filaments.
myosin filament one of the thick contractile filaments in a myofibril, composed mainly of myosin; each myosin filament is surrounded by six actin filaments.
one of the contractile elements in muscular fibers and other cells; in skeletal muscle, the actin filaments are about 7.5 nm wide and 1 mcm long, and attach to the transverse Z filaments.
Synonym(s): thin filament
Actin FilamentA long, slender chain of G-actin which transmits tension in muscles, participates in cell protrusion, and acts as scaffolding for binding dozens of different molecules. Actin filaments (AFs) can withstand molecular forces, but are highly sensitive to gelsolin.
Gelsolin cleaves AFs with almost surgical precision; gelsolin-actin cleavage is strictly regulated; micromolar concentrations of Ca2+ or a low pH cause gelsolin to sever; certain phosphoinositides inhibit severing, and may release gelsolin and allow AF growth. By EM, AFs are attached at one end to the Z bands and at the other interdigitate with myosin filaments.
ac·tin fil·a·ment(ak'tin fil'ă-mĕnt)
One of the contractile elements in muscular fibers and other cells; in skeletal muscle, the actin filaments are about 5 nm wide and 100 mcm long; they attach to the transverse Z filaments.