Cellular signal transduction refers to the movement of signals from outside the cell to the inside. Several distinct and diverse families of signal transduction mechanisms have been discovered - all of which cause alteration in cellular activity and/or changes in gene expression. Signal transduction can result from small molecules or ions (e.g. nitric oxide, steroids) moving into a cell, whereupon they bind to a cellular target and alter its activity. Other forms of cellular signal transduction involve the coupling of ligand-receptor interactions to intracellular events such as phosphorylation mediated by tyrosine kinases and/or serine/threonine kinases. The phosphorylated protein(s) exhibit altered activities.
Given the very large number of genes, proteins, and smaller biomolecules involved in cellular signal transduction, it is not possible for any supplier to provide suitable reagents for the study of all signal transduction mechanisms. And, although many of the molecules and pathways detailed in earlier sections of this catalog (notably reactive oxygen species and eicosanoids) are either involved in or can be used to study cellular signal transduction, the following pages are focused on reagents for the study of selected hormones (steroid hormones) and selected signal transduction mechanisms (nitric oxide and protein kinases). The latter includes antibodies to several phosphoprotein phosphatases, whose contributions to the regulation of kinase pathways have not yet been fully investigated.