CHARLOTTESVILLE, VA, Dec. 20, 2006 -- In a study recently published online by Developmental Biology, members of Dr. John Herr's laboratory at the University of Virginia Health System report the discovery of a new protein within a sperm's tail that could prove a key target for male contraceptive drugs.
"There's considerable interest in developing new male contraceptives," said Herr, who heads UVa's Center for Research in Contraceptive and Reproductive Health. "To support this effort, our team has been searching for proteins that might serve as target sites for small-molecule drugs."
The newly discovered protein is called sperm flagellar energy carrier (SFEC). It is the fourth in a family of proteins that perform transfer processes to help cells make and use energy. Inside the cell, these proteins operate much like a shuttle bus, binding and exchanging energy-carrying molecules known as ATP and ADP.
The discovery of SFEC has sparked interest among both basic scientists and contraceptive drug developers because of where it is located in the sperm and the kind of energy-making process that occurs there.
"One approach to male contraception is to disable sperm from swimming, and we think SFEC may be able to play a role in that process," Herr noted.
Dr. Young-Hwan Kim, the UVa researcher who discovered SFEC and led the study, found the new protein in the distal part of the sperm tail, or flagella. This was an unexpected finding because the three previously identified ATP/ADP carrier proteins reside in cell organelles called mitochondria. In sperm, the mitochondria reside in a region called the midpiece.
UVa researchers also found that SFEC has extensions at both ends of its amino acid sequence. Other ATP/ADP carriers do not have these extensions, which may explain why SFEC is able to perform its shuttling function in the distal sperm tail.