When most people think of cholesterol, they think of heart disease and blood, but cholesterol is actually the most abundant molecule in the outer membranes of mammalian cells and is vital for survival.

Gerald Feigenson, Cornell professor of molecular biology and genetics, has been creating simple models to mimic and study cholesterol in cell membranes for the past 15 years. He was recently given a boost with $937,000 in federal stimulus money from the American Recovery and Reinvestment Act (ARRA).

In popular parlance, doctors refer to "good cholesterol" (high-density lipoproteins) and "bad cholesterol" (low-density lipoproteins), but those terms actually refer to particles that contain molecules of proteins, fats and cholesterol. Feigenson's work focuses strictly on the cholesterol molecule and how it functions in cell membranes.

In cell membranes, cholesterol plays specific -- but little understood -- roles in organizing proteins of the membrane. For example, when insulin binds to a receptor on the outside of a cell, cholesterol is involved in getting information into the cell where it triggers a response. Similarly, cholesterol plays a role in the movement of viruses in and out of cells.

Feigenson's research was funded to measure the size and duration of nanodomains -- 2 to 100 nanometers in size -- where cholesterol molecules form different regions with distinct properties for proteins that come in contact with a cell's membrane. The nanodomains are too small to see, so Feigenson uses special fluorescence experiments to detect them.

"The size of these nanodomains might be so small that only one protein fits in there, and it might not come into contact with even one other protein," said Feigenson. "Nanodomains might be a way of isolating proteins until other signals appear, so their size and duration are crucial to their function."

The ARRA funds have already paid for temperature-control equipment for microscopes and new computers, and salaries for two graduate students and an undergraduate researcher.

"That's the spirit of this new government money," Feigenson said. "They want us to spend money fast."

In the spring, Feigenson plans to hire one or two more undergraduates. He will train them with a series of 15 lectures on lipid physical chemistry and the use of fluorescence markers and spectroscopic and microscopic techniques, before assigning them independent research within the project.

The project will also develop simple models to study how cholesterol works in the inner leaflet of the cell membrane.

Feigenson has also received an additional $59,623 in ARRA funds to buy equipment for a separate, ongoing National Institutes of Health-supported project.

So far, Cornell has received more than 90 ARRA grants, totaling almost $77 million.