National Cancer Institute researchers have teamed up with AxCell Biosciences to study how two families of proteins participate in signal transduction pathways, AxCell said Oct. 10.
The collaboration, which is still in preliminary stages, will employ AxCell’s technology for studying interactions between certain proteins and peptide sequences, and investigate the roles of two protein families, the serine-threonine and tyrosine kinases, in signal transduction. These two families of proteins are important in signal transduction because they add phosphate groups, or phosphorylate, other proteins, creating a cascade of phosphorylation events that carry messages within the cell. The NCI researchers, led by immunologist Steven Shaw, are hoping to learn what sites on a protein are susceptible to phosphorylation as a means of determining which proteins in the human proteome participate in signal transduction. John Rodwell, president and chief technical officer of AxCell, said the two groups got together after an NCI manager heard an AxCell presentation at a recent conference. The AxCell researchers had not yet studied phosphorylation in proteins, but the company’s technology offered a comprehensive way of studying the mechanism of phosphorylation, Shaw told ProteoMonitor. “It is essential to go about this systematically, rather than piecemeal as has been the norm in most labs in the past,” he said. “They have put together a set of infrastructure, patents, and informatics that allow them to be quite efficient in isolating domains, synthesizing peptides, and looking at the interactions between them.” Specifically, the two groups of scientists will use AxCell’s technology to synthesize specific peptide sequences that resemble fragments or proteins, or individual protein folds, Shaw said. Using an in vitro kinase assay, the researchers will investigate which peptide sequences the kinases phosphorylate with a radio-labeled phosphate group. “We’re working with Steve [Shaw] to predict what should be good substrates for these various kinases, we’re synthesizing them, and then we’re seeing if they do in fact behave as good substrates,” said Rodwell. “We study where these sequences occur in the human proteome, and that gives us a handle on what protein that particular kinase is acting on, and we can begin to build pathways on that basis.” Although the AxCell technology is based on an in vitro technique — in contrast to in vivo methods for studying protein interactions, such as yeast two-hybrid — Rodwell said that he has validated many of the interactions with other data. “Yeast two-hybrid is a nice system if [you’re studying] a specific pathway, but we’re taking a much more systems approach to study multiple pathways at the same time,” he said. Much of the data that the researchers generate will go towards populating AxCell’s ProChart database of protein interaction information, Rodwell said. AxCell is currently working with InforMax to integrate the ProChart database into InforMax’s GenoMax bioinformatics platform. Rodwell and Shaw said they are still working out the details of the collaboration, and have not yet signed a letter of intent, but that they expect the deal to go forward. — JSM