Knecht E, Roche E, Hernandez-Yago J, Vargas J L, Grisolia S
Biomed Biochim Acta. 1986;45(11-12):1575-83.
Low molecular weight phosphoryl compounds, such as carbamoyl phosphate, 2,3-diphosphoglycerate and phytic acid protect, to different extents, mitochondrial and cytosolic proteins such as ornithine transcarbamoylase (OTC), carbamoyl phosphate synthetase (CPS), glutamate dehydrogenase (GDH) and glyceraldehyde 3-phosphate dehydrogenase (GAPDH), from proteolytic inactivation (rat liver lysosomal extracts, pronase, elastase). Given the wide variety and common occurrence of low molecular weight reagents such as typified here, it seems that this kind of inhibition may be important in the regulation of protein turnover. Regulation of intracellular proteolysis can also occur via the proteolytic systems. Immunocytochemical procedures for mitochondrial enzymes (CPS, GDH, OTC), show intracellular homogeneity, but intercellular heterogeneity in rat liver, compatible with a role of the autophagic-lysosomal system in degrading these proteins. However, degradation of short-lived proteins occurs by other mechanisms. Using centrifugation of cultured cells, we find that the Golgi apparatus takes part in the degradation of these proteins, probably by controlling the traffic of proteins or proteases to the degradation site.
低分子量的磷酰化合物，如氨基甲酰磷酸、2,3-二磷酸甘油酸和植酸，能不同程度地保护线粒体和胞质蛋白，如鸟氨酸转氨甲酰酶（OTC）、氨基甲酰磷酸合成酶（CPS）、谷氨酸脱氢酶（GDH）和甘油醛-3-磷酸脱氢酶（GAPDH），使其免受蛋白水解失活（大鼠肝脏溶酶体提取物、链霉蛋白酶、弹性蛋白酶）。鉴于此处所代表的低分子量试剂种类繁多且普遍存在，这种抑制作用似乎在蛋白质周转的调节中可能很重要。细胞内蛋白水解的调节也可通过蛋白水解系统发生。针对线粒体酶（CPS、GDH、OTC）的免疫细胞化学程序显示，大鼠肝脏中细胞内具有同质性，但细胞间具有异质性，这与自噬溶酶体系统在降解这些蛋白质中的作用相一致。然而，短命蛋白的降解是通过其他机制发生的。通过对培养细胞进行离心，我们发现高尔基体参与了这些蛋白质的降解，可能是通过控制蛋白质或蛋白酶向降解位点的运输来实现的。
