Mole (MSR) and fractional (FSR) synthesis rates of proteins during C2C12 myoblast differentiation are investigated. Myoblast cultures supplemented with D₂O during 0–24 h or 72–96 h of differentiation are analyzed by LC‐MS/MS to calculate protein FSR and MSR after samples are spiked with yeast alcohol dehydrogenase (ADH1). Profiling of 153 proteins detected 70 significant (p ≤ 0.05, FDR ≤ 1%) differences in abundance between cell states. Early differentiation is enriched by clusters of ribosomal and heat shock proteins, whereas later differentiation is associated with actin filament binding. The median (first–third quartile) FSR (%/h) during early differentiation 4.1 (2.7–5.3) is approximately twofold greater than later differentiation 1.7 (1.0–2.2), equating to MSR of 0.64 (0.38–1.2) and 0.28 (0.1–0.5) fmol h⁻¹ µg⁻¹ total protein, respectively. MSR corresponds more closely with abundance data and highlights proteins associated with glycolytic processes and intermediate filament protein binding that are not evident among FSR data. Similarly, MSR during early differentiation accounts for 78% of the variation in protein abundance during later differentiation, whereas FSR accounts for 4%. Conclusively, the interpretation of protein synthesis data differs when reported in mole or fractional terms, which has consequences when studying the allocation of cellular resources.

中文翻译：

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C2C12 成肌细胞分化过程中蛋白质分子合成率的动态分析

研究了 C2C12 成肌细胞分化过程中蛋白质的摩尔 (MSR) 和分数 (FSR) 合成率。在 0-24 小时或 72-96 小时的分化过程中补充 D ₂ O 的成肌细胞培养物通过 LC-MS/MS 进行分析，以在样品中加入酵母醇脱氢酶 (ADH1) 后计算蛋白质 FSR 和 MSR。对 153 种蛋白质的分析检测到 70 种显着 ( p≤ 0.05, FDR ≤ 1%) 细胞状态之间的丰度差异。早期分化富含核糖体和热休克蛋白簇，而后期分化与肌动蛋白丝结合相关。早期分化 4.1 (2.7-5.3) 期间的中位（第一至第三四分位数）FSR (%/h) 大约是晚期分化 1.7 (1.0-2.2) 的两倍，相当于 MSR 为 0.64 (0.38-1.2) 和 0.28 ( 0.1–0.5) fmol h ⁻¹  µg ⁻¹总蛋白质，分别。MSR 与丰度数据更紧密地对应，并突出显示与糖酵解过程和中间丝蛋白结合相关的蛋白质，这些蛋白质在 FSR 数据中并不明显。同样，早期分化期间的 MSR 占后期分化期间蛋白质丰度变化的 78%，而 FSR 占 4%。最后，当以摩尔或分数形式报告时，对蛋白质合成数据的解释会有所不同，这在研究细胞资源的分配时会产生影响。