So unheard of was what researchers discovered in a protein associated with glaucoma that for over two years they ran it through a gauntlet of lab tests and published a new research paper on it. The tests validated what they initially saw.

It was a Y-shape. That made it an extreme oddity significant to science, and possibly someday to medicine, too, particularly in the treatment of certain types of blindness.

“A protein like this one has never been reported before. There are extremely few Y-shapes in proteins at all,” said Raquel Lieberman, who led the study. Lieberman is a structural biologist at the Georgia Institute of Technology, and an expert on myocilin, a protein sometimes implicated in a form of hereditary glaucoma.

There are other shapes in proteins that look similar to the Y, but there are key differences.

“Antibodies look a little like this, but in antibodies, separate proteins that are the products different genes fit together to make a kind of Y-shape,” Lieberman said. “This Y is encoded by one single gene sequence. That makes this absolutely unique.”

In addition to being the ostensible unicorn of protein structures, it turned out to be the central binding element of myocilin. The Y ties together major components to nail down myocilin’s overall form, overturning previous conceptions about the protein's appearance.

Although the Y hasn’t been particularly implicated in glaucoma, its existence could meaningfully alter the way researchers understand myocilin and how it works in the eye. When myocilin goes wrong, or “misfolds,” it makes fibrils that damage tissue called the trabecular meshwork that normally allows the fluid inside the eye to drain and relieve interior pressure.

“If you kill the cells that make this drainage work, it’s going to clog, and pressure inside the eye will increase,” said Lieberman, who is an associate professor in Georgia Tech’s School of Chemistry and Biochemistry. That pressure can kill parts of the retina or optic nerve, leading to irreversible partial or total blindness.

But though myocilin is common in many parts of our bodies, its normal, healthy role in the eye and, for that matter, what functions the protein has in the body at all are still a mystery.

“I think if we knew what this protein was doing in the trabecular meshwork, we would understand much more about glaucoma in general,” Lieberman said. “This research lets us know more about what myocilin is.”

Lieberman published her results on October 19, 2017, in the journal Structure.

The focus of studies so far has been on a part of myocilin that is the main culprit in a form of hereditary glaucoma, a protein structure called the olfactomedin domain, which Lieberman has also studied extensively. It looks like a protein propeller with five blades that surround a hole in the center.

“When a myocilin propellor misfolds, it unravels and forms amyloid fibrils that kill cells that maintain the trabecular network,” Lieberman said. "Until now, our work led us to believe that the propellers floated around individually as independent units, and not bound together in groups."

“All we knew before was that, in solution, those olfactomedins were just monomers. They didn’t seem to make up anything of a higher order, except when they unraveled into amyloid fibers, stuck together and blocked fluid flow,” Lieberman said.

The Y alters the picture. It anchors the propellers in groups of four. Two propellers (olfactomedin domains) each appear to be connected to either tip of the Y’s branches probably by amino acid strings. With the Y, the overall myocilin looks four pinwheels on strings tied to a slingshot.

Adding to the new discoveries: The Y itself is sticky, like glue. It’s even annoying to handle in the lab.

“It was sticking to the plastic, sticking to the glass, sticking to the membrane, to beads,” Lieberman said. “It’s super sticky. That ma