| Popis: |
Actin, one of the myofibrillar proteins of muscle, has one molecule of ADP very firmly bound to each subunit. In this study the firmly bound nucleotide has been used as a marker for actin synthesisin vivo, Myofibrils were prepared from limb muscles of mice of different ages, injected with 2.0 uCi/g body weight 3-adenosine and the specific activity of the bound ADP was determined following removal of unbound radioactivity by repeated washing. The adult rate of incorporation was low compared with the newborn rate. The results suggest that the rate of actin synthesis is high in the newborn but decreases markedly as the animal grows older. The amount of RNA associated with the myofibrils was also measured and was found to decline with age in a similar way to the rate of incorporation of label into actin. |
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