CO₂ in your blood opens hidden cell channels
Every time you breathe out, CO₂ levels in your blood briefly shift. But CO₂ does more than carry away waste gas: it opens tiny channels in cell membranes that normally stay shut…
Connexins are proteins that form small gateways in cell membranes. These gateways, called hemichannels, allow molecules to pass in or out of a cell. Under normal conditions they remain closed. But researchers discovered that the connexin connexin-43 (Cx43) responds strongly to CO₂ across the range naturally found in the body: 20 to 70 millimetres of mercury pressure.
A specific motif in the protein
How does Cx43 detect CO₂? The protein contains a specific segment, the carbamylation motif, that can bind CO₂ molecules directly. This changes the shape of the protein just enough to open the channel. The study, published in eLife, used multiple techniques to demonstrate this: dye loading in cells, measurements of electrical currents across membranes and real-time measurement of ATP release, where ATP is a signalling molecule that cells send outward when activated.
Targeted mutations in the carbamylation motif eliminated CO₂ sensitivity entirely. That confirms this specific segment of the protein is the key.
Relevance for aging and cell communication
Cx43 is one of the most common connexins in the human body. It plays roles in the heart, brain, skin and bone. As we age, connexin activity changes, disrupting communication between cells. If CO₂ levels switch these channels on, then any tissue with fluctuating CO₂ has a mechanism for regulating cell communication that has until now been overlooked.
This finding is fundamental in nature. Clinical applications are still far off. But it raises a new question: what role do CO₂-sensitive channels play in tissue aging?