In a technical tour de force, structural biologists funded by the National Institutes of Health have determined the three-dimensional structure of a molecule involved in HIV infection and in many forms of cancer. The high-resolution structure sheds light on how the molecule functions and could point to ways to control its activity, potentially locking out HIV and stalling cancer's spread.
The molecule, CXCR4, is part of a large family of proteins called G-protein coupled receptors (GPCRs). These molecules span the cell's membrane and transmit signals from the external environment to the cell's interior. GPCRs help control practically every bodily process, including cell growth, hormone secretion and light perception. Nearly half of all drugs on the market target these receptors.
"Scientists have been studying CXCR4 for years but have only been able to guess at what it looks like," said NIH Director Francis S. Collins, M.D., Ph.D. "Now that we have its structure, we have a much clearer picture of how this medically important molecule works, opening up entire new areas for drug discovery."
The researchers, led by Raymond C. Stevens, Ph.D., of the Scripps Research Institute in La Jolla, Calif., report their findings in the Oct. 7, 2010, advance online issue of the journal Science. The study received support from two major NIH initiatives: the structural biology program of the NIH Common Fund and the Protein Structure Initiative (PSI).
While a molecule called CD4 is the primary receptor for HIV, CD4 is not sufficient for the virus to penetrate cells. In 1996, a team of researchers at NIH's National Institute of Allergy and Infectious Diseases (NIAID) discovered that CXCR4 acts as a co-receptor by helping HIV enter cells.
Normally, CXCR4 helps activate the immune system and stimulate cell movement. But when the signals that activate the receptor aren't properly regulated, CXCR4 can spur the growth and sp
|Contact: Emily Carlson|
NIH/National Institute of General Medical Sciences