ISTOCK, MOLEKUUL Ribosomes, the cell’s protein-building machines that were thought to be indistinguishable from one another, have specialized functions, according to a pair of studies—one published earlier this month (June 1) in Cell and another published last week (June 15) in Molecular Cell.

“Until now, each of the 1 [million] to 10 million ribosomes within a cell has been thought to be identical and interchangeable,” study coauthor Maria Barna, a developmental biology and genetics professor at Stanford University, said in a statement. “Now we’re uncovering a new layer of control to gene expression that will have broad implications for basic science and human disease.”

In the first study, Barna and colleagues reported their findings that ribosomes accumulate different types of proteins around their outer shells, and that these proteins are associated with each ribosome’s function. In their latest study, the researchers discovered that ribosomes preferentially translated...