Puralpha与细胞周期蛋白A/细胞周期蛋白依赖性激酶2（Cdk2）的Cdk2部分的功能相互作用。

Functional interaction of Puralpha with the Cdk2 moiety of cyclin A/Cdk2.

作者信息

Liu Hong, Barr Sharon M, Chu Caryn, Kohtz D Stave, Kinoshita Yayoi, Johnson Edward M

机构信息

Department of Pathology, Mount Sinai School of Medicine, New York, NY 10029, USA.

出版信息

Biochem Biophys Res Commun. 2005 Mar 25;328(4):851-7. doi: 10.1016/j.bbrc.2005.01.038.

DOI:10.1016/j.bbrc.2005.01.038

PMID:15707957

Abstract

Puralpha is a sequence-specific single-stranded nucleic acid-binding protein and a member of the highly conserved Pur family. Puralpha has been shown to colocalize with cyclin A/Cdk2 and to coimmunoprecipitate with cyclin A during S-phase. Here we show that this interaction is mediated by a specific affinity of Puralpha for Cdk2. In pull-down assays GST-Puralpha efficiently binds Cdk2 and Cdk1, binds Cdk4 less efficiently, and does not display binding to Cdk6. Puralpha stimulates several-fold the phosphorylation in vitro of histone H1 by cyclin A/Cdk2, produced from baculovirus constructs. Double chromatin immunoprecipitation using antibodies to Cdk2 and Puralpha reveals that both proteins colocalize in HeLa cells to DNA segments upstream of the c-MYC gene. Pur family member Purgamma colocalizes with Cdk2 to a specific DNA segment in this region.

摘要

Puralpha是一种序列特异性单链核酸结合蛋白，属于高度保守的Pur家族成员。已表明Puralpha在S期与细胞周期蛋白A/Cdk2共定位，并与细胞周期蛋白A进行共免疫沉淀。在此我们表明，这种相互作用是由Puralpha对Cdk2的特异性亲和力介导的。在下拉实验中，GST-Puralpha能有效结合Cdk2和Cdk1，对Cdk4的结合效率较低，且不显示与Cdk6的结合。Puralpha能将杆状病毒构建体产生的细胞周期蛋白A/Cdk2对组蛋白H1的体外磷酸化作用提高数倍。使用针对Cdk2和Puralpha的抗体进行的双重染色质免疫沉淀显示，这两种蛋白在HeLa细胞中与c-MYC基因上游的DNA片段共定位。Pur家族成员Purgamma在该区域与Cdk2共定位于一个特定的DNA片段。