Receptor

Definition

A receptor is a specialized protein molecule that receives and transmits signals from outside the cell to elicit a cellular response. These proteins can be found on the cell surface or within the cell, and they play a critical role in cell signaling by binding to specific ligands such as hormones, neurotransmitters, or other signaling molecules. The binding activates various intracellular pathways, ultimately leading to physiological changes in the target cells.

5 Must Know Facts For Your Next Test

1. Receptors can be classified into different types, including G-protein-coupled receptors (GPCRs), ion channel receptors, and nuclear receptors, each having distinct mechanisms of action.
2. The specificity of receptor-ligand interactions is crucial; only specific ligands can bind to their respective receptors, which determines the biological effect.
3. Receptors can undergo desensitization, meaning that prolonged exposure to a ligand can lead to a decrease in receptor activity, impacting the cell's responsiveness.
4. Some receptors are located on the cell membrane while others are found in the cytoplasm or nucleus, allowing them to respond to different types of signaling molecules.
5. Mutations or dysfunctions in receptors can lead to various diseases, including cancer, diabetes, and neurological disorders due to altered signaling pathways.

Review Questions

• How do receptors contribute to the specificity of cellular responses to external signals?
  • Receptors contribute to the specificity of cellular responses by only binding to particular ligands that fit their structure. This selective binding ensures that only certain signals can activate specific receptors, leading to distinct biological responses. The combination of different receptors present on a cell also allows for nuanced regulation of various pathways and functions, ensuring that cells respond appropriately to their environment.
• Discuss the role of G-protein-coupled receptors (GPCRs) in signal transduction pathways.
  • G-protein-coupled receptors (GPCRs) play a pivotal role in signal transduction pathways by acting as intermediaries between extracellular signals and intracellular responses. When a ligand binds to a GPCR, it undergoes a conformational change that activates associated G-proteins inside the cell. This activation initiates a cascade of downstream signaling events involving various effector proteins, ultimately resulting in physiological changes such as gene expression or cellular metabolism.
• Evaluate how receptor mutations can impact cell signaling and contribute to disease states.
  • Receptor mutations can significantly disrupt normal cell signaling processes by altering how receptors interact with their ligands or affect their downstream signaling pathways. For example, mutations may lead to constitutive activation or loss of function of receptors, which can contribute to diseases such as cancer when growth factor receptors are constantly activated. Additionally, altered receptor functions in insulin or neurotransmitter systems can result in conditions like diabetes or mood disorders, showcasing how critical proper receptor function is for maintaining health.

Related terms

Ligand: A ligand is a molecule that binds specifically to a receptor to form a complex that triggers a biological response.

Signal Transduction: Signal transduction is the process by which a cell converts an external signal received by a receptor into a functional response, often involving multiple intracellular signaling pathways.

Endocrine Signaling: Endocrine signaling involves the release of hormones into the bloodstream that travel to distant target cells where they bind to specific receptors, initiating a response.