Phosphorylation signal detection on a peptide chip

An intracellular signal transduction system involved in many kinds of proteins regulates various cellular events, such as cellular proliferation, differentiation and cell death, responding to the outer environment. Among those proteins, protein kinases are one of the most important class of proteins. It has been reported that abnormal activities of protein kinases are related to various diseases. Therefore, an analysis of protein kinase activity would be useful for diagnosis and drug screening. Herein, we describe the detection of on-chip phosphorylation using a peptide chip by fluorescence imaging. In this work, we selected a cAMP-dependent protein kinase (PKA) as a model, and quantitatively evaluated the substrate specificity for PKA using a peptide chip. Moreover, we attempted to detect intracellular kinase activity. Since src correlates with breast cancer, we measured the src activity in MCF-7 human breast cancer cell lysate. Consequently, with our peptide chip we could detect the src activity in MCF-7 cell lysate. Therefore, this method could be applied to diagnosis, drug discovery and screening.