The Yeast ProtoArray from Protometrix contains some 5,000 proteins. Credit: ©PROTOMETRIX INC., USED WITH PERMISSION

Off-the-shelf protein arrays are just beginning to trickle onto the market. But most have been low-density antibody arrays for profiling cytokines, secreted proteins that act as intercellular chemical messengers. Panomics of Redwood City, California, produces TranSignal Human Cytokine Antibody Array 2.0 for profiling the expression of 21 well-studied human cytokines. The array uses standard chemiluminescence detection and detects soluble cytokines at concentrations in the picogram per millilitre range. Zyomyx of Hayward, California, offers a human cytokine biochip for profiling 30 cytokines, which is sold for use with its Protein Profiling Biochip System, which includes an automated workstation, biochip reader and data-analysis software.

BD Biosciences Clontech in Palo Alto, California, sells an off-the-shelf antibody array for detecting a variety of cytosolic and membrane-bound proteins relevant to signal transduction, cell-cycle regulation, gene transcription and apoptosis. Its Antibody Microarray 500 contains over 500 antibodies printed on a standard-size (75 × 25 × 1 mm) glass slide and uses fluorescence-based detection. It is designed for qualitative rather than quantitative analysis but can detect differences in protein abundance between two samples with detection limits of 20 pg ml−1 for each protein target.

On the protein-function microarray front, Protometrix of Branford, Connecticut, will later this year roll out its first product, the Yeast ProtoArray, which stems from the pioneering protein microarray work of Michael Snyder's group at Yale University. This 'proteome' microarray will contain some 5,000 proteins in the Saccharomyces cerevisiae (yeast) proteome, including over 1,500 with significant homology to human proteins.

“The biggest bottleneck for everybody is still content,” says Barry Schweitzer, Protometrix's senior director for technology. The company has now industrialized the cloning, expression and protein-purification process. “It's just a factory running 24/7,” he says. “Everything that we clone we also have to sequence.” The Yeast ProtoArray is targeted more towards the research market but Protometrix expects to follow this up with products of direct relevance to drug discovery.