Key result
Cardiac contractile proteins show differential molar synthesis rates from shared precursor pools, led by actin.
Why the study?
The relative molar synthesis of cardiac contractile proteins and their precursor pools under control haemodynamic conditions was not fully characterized.
This preclinical study demonstrates that cardiac contractile proteins are synthesized from the same precursor pools at varying relative molar rates.
No immediate clinical implications; leaves open whether synthesis hierarchies apply to human hearts in vivo.
The relative molar synthesis of cardiac contractile proteins has been measured in the perfused heart under control haemodynamic conditions. This synthesis, of myosin heavy chains, individual light chains (1 and 2), actin and tropomyosin, was determined from isolated guinea-pig hearts perfused for 3h simultaneously with constant specific radioactivities and concentrations of [3H]lysine and [3H]phenylalanine. The data strongly suggest that all of the proteins studied were synthesized from the same precursor pools of lysine and phenylalanine, since the ratio of the specific activities of the two labels was the same in all of the proteins. Measurement of molar synthesis of each contractile protein was the same with either labelled amino acid. Under control haemodynamic-perfusion conditions, the relative molar synthesis of the contractile proteins was actin greater than heavy chains greater than light chain 2 greater than light chain 1 greater than tropomyosin.
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Evans et al. (1981) studied this question. Perfusion with [3H]lysine and [3H]phenylalanine was evaluated on Relative molar synthesis of cardiac contractile proteins. In isolated guinea-pig hearts, the relative molar synthesis of contractile proteins was actin > heavy chains > light chain 2 > light chain 1 > tropomyosin, synthesized from the same precursor pools.
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