Cell signaling (Page 2)

Master’s-Level Cell Biology & Advanced Molecular Biology Notes 1. Definition JAK–STAT signaling is a relatively direct mechanism by which extracellular signals, particularly cytokines, interferons, growth factors, and some hormones, regulate gene expression. The pathway consists of two major components: Unlike RTK signaling, where receptor kinase activity is intrinsic to the receptor, many JAK–STAT receptors lack intrinsic kinase activity and depend on receptor-associated JAKs. Core pathway 2. Why Is It Called JAK–STAT? JAK Janus kinase Named for the Roman god Janus because JAK proteins contain important kinase-related domains with distinct regulatory functions. STAT Signal Transducer and Activator of Transcription STAT proteins perform two roles: Thus, theRead More →

Master’s-Level Cell Biology & Advanced Molecular Biology Notes 1. Definition G-protein-coupled receptors (GPCRs) are a large family of cell-surface receptors characterized by seven transmembrane α-helical domains that transduce extracellular signals into intracellular responses through heterotrimeric G proteins and associated signaling pathways. GPCRs respond to diverse ligands including: They regulate: 2. Basic GPCR Architecture A GPCR contains: The seven helices are conventionally numbered: TM1 → TM7 3. The Heterotrimeric G Protein The classical signaling partner of a GPCR is a heterotrimeric G protein consisting of: The Gα subunit binds guanine nucleotides: 4. The Central GPCR Signaling Cycle The core mechanism is: 5. Inactive State In theRead More →

Master’s-Level Cell Biology & Advanced Molecular Biology Notes 1. Definition A receptor–ligand interaction is the specific, usually reversible binding of a signaling molecule (ligand) to a complementary receptor, resulting in a conformational or organizational change that initiates or modifies cellular signaling. General principle The ligand provides the information, while the receptor detects and converts that information into a cellular response. 2. What Is a Ligand? A ligand is a molecule that binds specifically to a receptor. Examples include: Peptides and proteins Small molecules Lipid-derived molecules Gases Extracellular matrix ligands 3. What Is a Receptor? A receptor is a macromolecular sensor, usually a protein, that recognizesRead More →