Rabault B, Ghysdael J
Laboratoire d'Oncologie Virale et Cellulaire, CNRS URA 1443, Institut Curie, Centre Universitaire, Orsay, France.
J Biol Chem. 1994 Nov 11;269(45):28143-51.
Ets1, the founding member of the Ets gene family of transcriptional regulators, is a phosphoprotein which is highly expressed in cells of the T and B lymphoid lineages. Previous studies have shown that Ets1 becomes rapidly and transiently phosphorylated following antigen receptor (T cell (antigen) receptor (TCR) and membrane Ig) triggering a response which is absolutely dependent on ligand-induced calcium mobilization. By a combination of two-dimensional tryptic phosphopeptide and mutational analyses, the target residues of these calcium-dependent phosphorylation events are identified as 4 serine residues clustered in a domain of Ets1 adjacent to its DNA binding domain (Ets domain). From the comparison of the properties of wild type Ets1 with those of mutant proteins carrying serine-to-alanine substitution in target residues, calcium-dependent phosphorylation of Ets1 is shown to inhibit its binding to specific DNA sequences but does not affect its ability to accumulate in the nucleus, another property dependent on the Ets domain. Our data are consistent with a model in which the calcium-dependent phosphorylation of Ets1 represent the first step of a general clearance of Ets1 function during T and B cell activation.
Ets1是转录调节因子Ets基因家族的创始成员，是一种磷蛋白，在T和B淋巴细胞谱系的细胞中高度表达。先前的研究表明，抗原受体（T细胞（抗原）受体（TCR）和膜免疫球蛋白）触发反应后，Ets1会迅速且短暂地磷酸化，该反应绝对依赖于配体诱导的钙动员。通过二维胰蛋白酶磷酸肽分析和突变分析相结合的方法，这些钙依赖性磷酸化事件的靶残基被确定为聚集在Ets1与其DNA结合域（Ets结构域）相邻区域的4个丝氨酸残基。通过比较野生型Ets1与在靶残基中携带丝氨酸到丙氨酸替代的突变蛋白的特性，发现Ets1的钙依赖性磷酸化会抑制其与特定DNA序列的结合，但不影响其在细胞核中积累的能力，这是另一种依赖于Ets结构域的特性。我们的数据与一个模型一致，即在T和B细胞激活过程中，Ets1的钙依赖性磷酸化代表了Ets1功能普遍清除的第一步。
