Wefes I, Mastrandrea L D, Haldeman M, Koury S T, Tamburlin J, Pickart C M, Finley D
Department of Cell Biology, Harvard Medical School, Boston, MA 02115, USA.
Proc Natl Acad Sci U S A. 1995 May 23;92(11):4982-6. doi: 10.1073/pnas.92.11.4982.
A global cellular reorganization occurs during the reticulocyte stage of erythroid differentiation. This reorganization is accomplished partly through programmed protein degradation. The selection of proteins for degradation can be mediated by covalent attachment of ubiquitin. We have cloned cDNAs encoding two ubiquitin-conjugating (E2) enzymes, E2-20K and E2-230K, and found their genes to be strongly induced during the differentiation of erythroblasts into reticulocytes. Induction of the E2-20K and E2-230K genes is specific, as transcript levels for at least two other ubiquitinating enzymes fall during erythroblast differentiation. In contrast to most proteins induced in reticulocytes, E2-20K and E2-230K enzymes are present at strongly reduced levels in erythrocytes and thus decline in abundance as reticulocyte maturation is completed. This result suggests that both enzymes function during the reticulocyte stage, when enhanced protein degradation has been observed. These data implicate regulated components of the ubiquitin conjugation machinery in erythroid differentiation.
在红细胞分化的网织红细胞阶段会发生全球性的细胞重组。这种重组部分是通过程序性蛋白质降解来完成的。蛋白质降解的选择可以由泛素的共价连接介导。我们已经克隆了编码两种泛素结合（E2）酶E2-20K和E2-230K的cDNA，并发现它们的基因在成红细胞分化为网织红细胞的过程中被强烈诱导。E2-20K和E2-230K基因的诱导是特异性的，因为至少另外两种泛素化酶的转录水平在成红细胞分化过程中下降。与网织红细胞中诱导产生的大多数蛋白质不同，E2-20K和E2-230K酶在红细胞中的水平大幅降低，因此随着网织红细胞成熟的完成，其丰度下降。这一结果表明，这两种酶在网织红细胞阶段发挥作用，此时已观察到蛋白质降解增强。这些数据表明泛素结合机制的调控成分参与了红细胞分化。
