The fragile X protein family consists of three RNA-binding proteins involved in translational regulation. Fragile X mental retardation protein (FMRP) is well-studied, as its loss leads to fragile X syndrome, a neurodevelopmental disorder which is the most prevalent form of inherited mental retardation and the primary monogenetic cause of autism. Fragile X related proteins 1 and 2 (FXR1P and FXR2P) are autosomal paralogs of FMRP that are involved in promoting muscle development and neural development, respectively. There is great interest in studying this family of proteins, yet researchers have faced much difficulty in expressing and purifying the full-length versions of these proteins in sufficient quantities. We have developed a simple, rapid, and inexpensive procedure that allows for the recombinant expression and purification of full-length human FMRP, FXR1P, and FXR2P from Escherichia coli in high yields, free of protein and nucleic acid contamination. In order to assess the proteins' function after purification, we confirmed their binding to pseudoknot and G-quadruplex forming RNAs as well as their ability to regulate translation in vitro.

We examine the price and variety of a sample of consumer goods at the barcode level in cities within China. Unlike the position in the United States, in China the prices of goods tend to be lower in larger cities. We explain that difference between the countries by the more uneven spatial distribution of manufacturers' sales and retailers in China, and we confirm the pro-competitive effect of city size on reducing markups there. In both countries, there is a greater variety of goods in larger cities, but that effect is more pronounced in China. Combining the lower prices and greater variety, the price indexes in China for the goods we study fall with city size by around seven times more than in the United States.