Protein microarrays for gene expression and antibody screening

Proteins translate genomic sequence information into function, enabling bio logical processes. As a complementary approach to gene expression profiling on cDNA microarrays, we have developed a technique for high-throughput gen e expression and antibody screening on chip-size protein microarrays, Using a picking/spotting robot equipped with a new transfer stamp, protein solut ions were gridded onto polyvinylidene difluoride filters at high density, S pecific purified protein was detected on the filters with high sensitivity (250 amol or 10 pg of a test protein). On a microarray made from bacterial lysates of 92 human cDNA clones expressed in a microtiter plate, putative p rotein expressors could be reliably identified. The rate of false-positive clones, expressing proteins in incorrect reading frames, was low. Product s pecificity of selected clones was confirmed on identical microarrays using monoclonal antibodies. Cross-reactivities of some antibodies with unrelated proteins imply the use of protein microarrays for antibody specificity scr eening against whole libraries of proteins, Because this application would not be restricted to antigen-antibody systems, protein microarrays should p rovide a general resource for high-throughput screens of gene expression an d receptor-ligand interactions. (C) 1999 Academic Press.