Structure-function analysis of GNIP, the glycogenin-interacting protein.
Structure-function analysis of GNIP, the glycogenin-interacting protein.
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DOI：
10.1016/j.abb.2003.11.017
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发表时间：
2004-01
影响因子：
3.9
通讯作者：
L. Zhai;A. Dietrich;A. V. Skurat;P. Roach
中科院分区：
文献类型：
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作者：
L. Zhai;A. Dietrich;A. V. Skurat;P. Roach
糖原是一种自我葡萄糖基化的蛋白质，启动糖原的生物合成。我们最近鉴定了一个蛋白质家族，GNIP，其与糖原配基相互作用并刺激其自身葡糖基化活性[J. Biol. Chem. 277（2002）19331]。GNIP基因（也称为TRIM 7）编码至少四种不同的GNIP亚型，其中三种（GNIP 1、GNIP 2和GNIP 3）共有一个COOH末端B30.2结构域和预测的卷曲螺旋区。基于Western印迹分析，GNIP 1蛋白广泛分布于组织中。利用酵母双杂交系统对GNIP 2的一系列缺失突变体进行分析，发现B30.2结构域负责与糖原的相互作用。截短形式的重组GNIP 2，缺乏NH 2-末端卷曲螺旋区，交联糖原通过戊二醛处理，支持的想法，B30.2域是足够的相互作用。在这项研究的过程中，还发现GNIP 2通过卷曲螺旋结构域与自身相互作用。还检测到GNIP 1和GNIP 2之间的杂环相互作用。由于糖原也是二聚体，糖原和GNIP之间的更高阶多聚体复合物将是可能的。
Glycogenin is a self-glucosylating protein that initiates glycogen biosynthesis. We recently identified a family of proteins, GNIPs, that interact with glycogenin and stimulate its self-glucosylating activity [J. Biol. Chem. 277 (2002) 19331]. The GNIP gene (also called TRIM7) encodes at least four distinct isoforms of GNIP, three of which (GNIP1, GNIP2, and GNIP3) have in common a COOH-terminal B30.2 domain and predicted coiled-coil regions. Based on Western blot analysis, the GNIP1 protein is widely distributed in tissues. From analysis of a series of deletion mutants of GNIP2 using the yeast two-hybrid system, the B30.2 domain was found to be responsible for the interaction with glycogenin. A truncated form of recombinant GNIP2, lacking the NH2-terminal coiled-coil region, was cross-linked to glycogenin by glutaraldehyde treatment, supporting the idea that the B30.2 domain was sufficient for the interaction. In the course of this study, GNIP2 was also found to interact with itself, via the coiled-coil domain. Heterologous interactions between GNIP1 and GNIP2 were also detected. Since glycogenin is also a dimer, higher order multimeric complexes between glycogenin and GNIPs would be possible.