G-Protein and G-Protein Coupled Receptors: Implications in Regulation of Immune Response

Abstract

The guanine nucleotide binding proteins (G proteins) act as molecular switches of ‘on’ and ‘off’ when bound to GTP and GDP respectively while the guanine protein coupled receptors (GPCRs) are membrane bound receptors whereby extracellular substances (ligands)communicate signals from these substances to an intracellular molecule the G-proteins which in turn bind and activate or inhibit downstream effect or molecules causing cellular responses. This review is aimed at exploring the concept and mechanism of G-proteins and GPCR and their implication in immune response. The GPCR can be activated by various physiological or pathological processes cellular metabolism, hormones, neuro-transmitters, chemokines, autocrines, paracrines, endocrine and exocrine secretions which play an important role in relaying or routing signals to several intracellular pathways. The signal transduction by the extracellular activation or inhibition of the GPCR mediate metabolic enzymes, ion channels, transporters, cellular gene transcription, migration, survival, activation, differentiation and cytokine secretion of immune cells resulting in the synthesis and regulation of embryonic development, gonadal development, learning /memory organismal homeostasis, hematopoiesis and immune dynamics. Therefore, G proteins and GPCRs signaling systems are key determinants in innate and adaptive immunity. The signal transduction of G-Protein and GPCR by cytokine chemotaxis as Chronic inflammatory mediators is associated with tumorigenesis, metastasis with potential antagonism for appropriate targeted therapy.