But a new study, led by biologists at the University of California, Berkeley, and due to be published June 22 in the journal Genetics, may help clarify the mystery by giving additional evidence that the Rh protein serves as a gas channel for carbon dioxide (CO2).
The study's conclusions, the researchers said, will lead to new directions in human and animal physiology research, as well as generate lively debate among biochemists and hematologists.
"This has implications for understanding how humans breathe, how we control the acidity (pH) of various fluids in our bodies and how our kidneys function, all of which rely upon movement of CO2 across cell membranes," said Sydney Kustu, professor of plant and microbial biology at UC Berkeley's College of Natural Resources and principal investigator of the study.
Kustu noted that scientists had long doubted the presence of protein channels for CO2 or any gases. This is because gases typically have no trouble crossing cell membranes unaided, so it was not suspected that the Rh protein would play such a role.
But among gases, carbon dioxide (CO2) and ammonia (NH3) are exceptional, the researchers explained. They both dissolve readily in water, which can slow their passage across oily membranes.
Recent evidence indicates that ammonium/methylammonium transporter (Amt) proteins act as gas channels for NH3. Unlike active transporters, channels allow multiple molecules of gas to move through at the same time, an important distinction for gases that need to move acr
Contact: Sarah Yang
University of California - Berkeley