Signal Transduction Antibodies

Cell surface receptors transduce signals from the exterior of the cell to the interior by binding to secreted or extracellular factors, including hormones, growth factors, neurotransmitters, or other molecules. Cell surface receptors are generally classified by their tertiary structure or their membrane topology. Cell surface receptors include enzyme-linked receptors, G-protein coupled receptors and ion channel-linked receptors. Transduction of the intracellular signal can be mediated by protein-protein interactions by effector proteins, or by enzymatic activity as in the case of the enzyme-linked receptors. The enzyme-linked receptors usually possess enzymatic activity themselves, or associate with kinases or other enzymatic proteins intracellularly.

After binding of a ligand or secreted factor to its cell surface receptor, an intracellular signal is transduced, which is mediated by enzymatic activity of the receptor itself, as in the case of receptor tyrosine kinases, and by effector or adaptor proteins bound to specific intracellular domains of the receptor.

Phosphorylation is a major post-translational modification to proteins and controls cell signaling and induction of cell proliferation, differentiation, cell death and other biological processes. Phosphatases reverse phosphorylation by removing the phosphate group added by kinases mostly to serine, threonine or tyrosine residues in a protein. Thus phosphatases have a critical role in regulating cell signaling, as generally reversal of the phosphorylation indicates a switching off of the signal. Uncontrolled or constitutive signaling by cell surface receptors may lead to increased proliferation, among other outcomes, and could lead to the pathogenesis of cancer and other diseases. Therefore, after phosphorylation and protein activation by kinases, the signal must return to the resting or inactivated state through dephosphorylation catalyzed by phosphatases.

Growth factors, peptide hormones, neurotransmitters and other secreted molecules initiate diverse signals involved in controlling cellular growth and proliferation, tissue development and differentiation, cellular metabolism and other biological processes. They initiate signals by binding to a receptor on the cell surface, which then undergoes a conformational change leading to an intracellular signaling cascade.