Offer G, Starr R, Trinick J
Muscle Biology Division, AFRC Institute of Food Research-Bristol Laboratory, Langford, UK.
Adv Exp Med Biol. 1988;226:61-73.
F-protein, a consistent contaminant of myosin preparations, has been shown to be phosphofructokinase, the key regulatory enzyme of glycolysis. In homogenates of rigor muscle most of the phosphofructokinase sediments with the myofibrils, suggesting that in the living muscle cell phosphofructokinase is not in the soluble fraction as was formerly thought, but bound to the myofibrils. Fluorescent antibody to F-protein labels myofibrils in a zone in each half of the A-band. The increase in separation of the zones across the A-band with increase in sarcomere length suggests that the antibody binds to the parts of the cross-bridge regions of the thick filament within the H-zone. It therefore seems likely that phosphofructokinase is located in the cross-bridge region of the thick filament, but that access of antibody is restricted by overlapping thin filaments.
F蛋白是肌球蛋白制剂中一种常见的污染物，已被证明是磷酸果糖激酶，即糖酵解的关键调节酶。在僵直肌肉的匀浆中，大部分磷酸果糖激酶与肌原纤维一起沉淀，这表明在活的肌肉细胞中，磷酸果糖激酶并不像以前认为的那样存在于可溶性部分，而是与肌原纤维结合。针对F蛋白的荧光抗体在A带每一半的一个区域标记肌原纤维。随着肌节长度增加，A带两侧区域分离度增加，这表明抗体与H区内粗肌丝横桥区域的部分结合。因此，磷酸果糖激酶似乎位于粗肌丝的横桥区域，但抗体的进入受到重叠细肌丝的限制。
