A recent discovery is shaking up how scientists study proteins – and it’s all due to mice. Most mice already travel impressive distances; they have been observed to travel over 10 kilometers in one night on an exercise wheel. However, in 2015, molecular biologist Eric Olson of the University of Texas Southwestern Medical Center in Dallas unveiled a type of mouse that could go farther than any other rodent on a treadmill without slipping. They could travel for 90 minutes up a steep 10% grade without faltering, and performed 31% better than other rodents. These mice differed from other mice in only one way – one muscle protein had been removed.
There are muscle proteins with over 30,000 amino acids, such as Titrin, a protein that involves muscle elasticity. However, the protein removed from these mice is not so impressive; It is only made up of a measly 46 amino acids. However, when removed, it “takes the brakes off” of muscular performance, meaning organisms without it can go harder, faster, and longer. For over 150 years, researchers overlooked the huge impact that this small protein, called myoregulin, has on muscle function.
Scientists, including Olson, began to realize that their initial method for looking at genomes involving proteins did not include the analysis of these tiny, microproteins. After this discovery, new methods of analysis have allowed researchers to find and look at the tinier proteins. Biochemist Jonathan Weissman of the University of California, San Francisco remarks, “for the first time, we are about to explore this universe of new proteins.” Discoveries in this field are even leading to the research of microproteins in humans.
While they may be smaller in size than other proteins, their size allows them to jam the processes of the larger proteins, and can both unleash or inhibit these processes. Functions of microproteins found earlier include bolstering of immune systems, controlling destruction of faulty RNA, protecting bacteria from extreme temperatures, determining when plants flower, and adding toxicity to the venom of some organisms. Scientists predict that microproteins will be involved in nearly all biological processes, and that they just hadn’t thought to look for them before. It is also expected that with the study of microproteins, the study of the genome will have to be rethought or revised. This is because many microproteins seem to be encoded in DNA and RNA. Microproteins were never taken into account when studying the genome. According to Gisela Storz of the National Institute of Child Health and Human Development in Bethesda, Maryland, “we need to rethink what genes are.”
Scientists have already begun to test potential uses and purposes for microproteins. Companies have begun to sell products derived from these microproteins, such as insecticides derived from the venom of the Australian funnel-web spider. A clinical trial is currently testing an imaging agent derived from another tiny protein found in scorpion venom, intended to highlight the edges of tumors more easily in scans so that doctors can treat them more accurately. Microproteins are now in higher demand for drug companies – microproteins are now one of the most rapidly growing areas of medical research.