ABSTRACT
Ion channels represent a diverse group of integral membrane proteins that regulate the passage of ions across cell membranes. They are ubiquitously expressed throughout the body and are essential for important physiological processes such as regulation of membrane potential, signal transduction, and cellular plasticity. Protein phosphorylation mediates many basic cellular processes, including metabolism, growth, division, differentiation, motility, organelle trafficking, membrane transport, muscle contraction, immunity, learning, and memory. Nuclear receptors are transcription factors that are fundamental in embryonic development, maintenance of differentiated cellular phenotypes, metabolism, and cell death. Defective nuclear receptor signaling is implicated in cancer, infertility, obesity, and diabetes. The third pathway is associated with signaling by growth factors and is followed by the induction of receptor tyrosine kinases and effector proteins.
