Gunnewiek J M, van Aarssen Y, Wassenaar R, Legrain P, van Venrooij W J, Nelissen R L
Department of Biochemistry, University of Nijmegen, The Netherlands.
Nucleic Acids Res. 1995 Dec 11;23(23):4864-71. doi: 10.1093/nar/23.23.4864.
The U1 snRNP-specific protein C contains an N-terminal zinc finger-like CH motif which is required for the binding of the U1C protein to the U1 snRNP particle. Recently a similar motif was reported to be essential for in vivo homodimerization of the yeast splicing factor PRP9. In the present study we demonstrate that the human U1C protein is able to form homodimers as well. U1C homodimers are found when (i) the human U1C protein is expressed in Escherichia coli, (ii) immunoprecipitations with anti-U1C antibodies are performed on in vitro translated U1C, and when (iii) the yeast two hybrid system is used. Analyses of mutant U1C proteins in an in vitro dimerization assay and the yeast two hybrid system revealed that amino acids within the CH motif, i.e. between positions 22 and 30, are required for homodimerization.
U1小核核糖核蛋白特异性蛋白C含有一个N端锌指样CH基序，该基序是U1C蛋白与U1小核核糖核蛋白颗粒结合所必需的。最近有报道称，类似的基序对于酵母剪接因子PRP9的体内同源二聚化至关重要。在本研究中，我们证明人类U1C蛋白也能够形成同源二聚体。当（i）人类U1C蛋白在大肠杆菌中表达时，（ii）用抗U1C抗体对体外翻译的U1C进行免疫沉淀时，以及（iii）使用酵母双杂交系统时，均可发现U1C同源二聚体。在体外二聚化试验和酵母双杂交系统中对突变型U1C蛋白的分析表明，CH基序内即22至30位之间的氨基酸对于同源二聚化是必需的。
