THE DEGRADATION OF ENDOGENOUS AND EXOGENOUS PROTEINS IN CULTURED SMOOTH-MUSCLE CELLS
THE DEGRADATION OF ENDOGENOUS AND EXOGENOUS PROTEINS IN CULTURED SMOOTH-MUSCLE CELLS
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DOI：
10.1016/0304-4165(82)90113-1
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发表时间：
1982-01-01
期刊：
影响因子：
--
通讯作者：
VANDERWESTHUYZEN, DR
中科院分区：
文献类型：
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作者：
BATES, PJ;COETZEE, GA;VANDERWESTHUYZEN, DR
将培养的[牛]平滑肌细胞中内源性蛋白质降解途径与内吞LDL [低密度脂蛋白]的载脂蛋白B降解中涉及的充分表征的溶酶体途径进行比较。在溶酶体对125 I标记的LDL的活性几乎完全被氯喹和/或氯化铵抑制的条件下，通过释放[3 H]Phe评估的短寿命和异常蛋白质的降解仅减少10- 17%。长寿命蛋白质降解的基础速率降低了约30%，而在营养不良条件下发现的加速蛋白水解可以完全由这些溶酶体营养剂定义的溶酶体系统解释。温度研究表明，长寿蛋白质（Ea [活化能] = 18千卡/摩尔）和短命蛋白质（Ea = 10千卡/摩尔）的降解机制之间存在差异。内源性蛋白质降解的Arrhenius图显示在15 ℃之间没有转换。和37度。与LDL的分解相反，LDL的分解在低于20 ℃时停止。C.快速周转蛋白的降解显然主要是在溶酶体外，而长寿命蛋白的显著降解也发生在溶酶体外。
The pathways of degradation followed by endogenous proteins in cultured [bovine] smooth muscle cells were comapred with the well-characterized lysosomal pathway involved in the degradation of apolipoprotein B of endocytosed LDL [low density lipoprotein]. Under conditions in which lysosomal activity towards 125I-labeled LDL was almost completely inhibited by chloroquine and/or ammonium chloride, the degradation of short-lived and abnormal proteins, assessed by the release of [3H]Phe, was reduced by only 10-17%. The basal rate of degradation of long-lived proteins was reduced by .apprx. 30% by the same inhibitors while the accelerated proteolysis found under nutrient-poor conditions could be completely accounted for by the lysosomal system as defined by these lysosomotrophic agents. Temperature studies indicated differences between the mechanisms involved in the degradation of long-lived proteins (Ea [activation energy] = 18 kcal/mol) and short-lived proteins (Ea = 10 kcal/mol). Arrhenius plots for the degradation of endogenous proteins showed no transitions between 15.degree. and 37.degree. C in contrast to the breakdown of LDL which ceased below 20.degree. C. The degradation of rapid-turnover proteins is apparently largely extralysosomal and a significant breakdown of long-lived proteins also occurs outside lysosomes.