Signaling receptors & Cellular response.pptx

Signaling receptors & Cellular response.pptx

1. Signaling receptors & Cellular response Dr Showkat Ahmad Wani

2. Introduction

3. Types of Signaling Receptors Receptors are usually proteins that detect extracellular signals and transmit them inside the cell. Broadly classified into: A. Cell-surface Receptors (Extracellular signals cannot cross membrane directly) G-Protein Coupled Receptors (GPCRs) 7-transmembrane domain proteins. Bind ligand → activate G-protein → trigger second messengers (cAMP, IP3, DAG, Ca²⁺). Examples: Adrenergic receptors (epinephrine), Rhodopsin (vision). Enzyme-linked Receptors Mostly Receptor Tyrosine Kinases (RTKs) . Ligand binding → receptor dimerization → autophosphorylation → downstream signaling (MAPK, PI3K pathways). Examples: Insulin receptor, EGFR. Ion Channel Receptors (Ligand-gated ion channels) Binding of neurotransmitter opens/closes ion channels. Rapid electrical responses in neurons, muscles. Examples: Nicotinic acetylcholine receptor, GABA receptor.

4. Signal Transduction Pathways

5. Cellular Responses Cells respond differently depending on the type of signal and receptor: Metabolic regulation (e.g., insulin → glucose uptake & glycogen synthesis). Gene expression changes (e.g., steroid hormones → activate transcription). Cytoskeletal changes & movement (e.g., chemokines guiding immune cells). Electrical responses (e.g., neurotransmitters in neurons). Cell fate decisions (division, differentiation, apoptosis).

6. Importance of Signaling Receptors

7. Summary Receptors = cell’s “antennae” to sense environment. Two main types: cell-surface receptors (GPCRs, RTKs, ion channels) & intracellular receptors . Signal transduction → cascades, amplification, second messengers. Final output = cellular response (metabolism, gene expression, movement, survival).

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