Shining a Light on the World of Microproteins

You could be forgiven for assuming that scientists know how many kinds of proteins exist. After all, researchers have been studying proteins for more than two centuries. They have powerful tools in their labs to search for the molecules. They can scan entire genomes, spotting the genes that encode proteins. They can use artificial intelligence to help decipher the complex shapes that allow proteins to do their jobs, whether that job entails catching odors in our noses or delivering oxygen in our blood. But the world of proteins remains remarkably mysterious. It turns out that a vast number of them have been hiding in plain sight. In a study published on Thursday, scientists revealed 4,208 previously unknown proteins that are made by viruses such as influenza and H.I.V. Researchers elsewhere have been uncovering thousands of other new proteins in bacteria, plants, animals and even humans. Many of these newly discovered proteins probably play a vital role in life, according to Thomas Martínez, a biochemist at the University of California, Irvine. “There is no way to get around this,” he said. “If we ever want to understand fully how our biology works, we have to have a complete accounting of all the parts.” For a long time, scientists depended on luck to find new proteins. In 1840, for example, Friedrich Ludwig Hünefeld, a German chemist, became curious about earthworm blood. He collected blood from a worm and put it on a glass slide. When he looked through a microscope, Hünefeld noticed platelike crystals: He had discovered hemoglobin.