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What are the different types of hormone receptors?

Hormone receptors are specialized proteins found on the surface or inside cells that bind to specific hormones. These receptors play a crucial role in transmitting signals from hormones to cells, thereby regulating various physiological processes in the body.

1. Membrane-bound receptors

Membrane-bound receptors are located on the cell surface and are typically involved in the signaling of peptide hormones, such as insulin and growth hormone. These receptors have an extracellular domain that binds to the hormone and an intracellular domain that initiates a signaling cascade within the cell.

2. Intracellular receptors

Intracellular receptors are found inside the cell, usually in the cytoplasm or nucleus. They primarily bind to lipid-soluble hormones, such as steroid hormones (e.g., estrogen and testosterone) and thyroid hormones. Once the hormone binds to the receptor, the hormone-receptor complex translocates to the nucleus and directly influences gene expression.

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3. G protein-coupled receptors (GPCRs)

G protein-coupled receptors are a large family of membrane-bound receptors that are involved in the signaling of various hormones, neurotransmitters, and other signaling molecules. These receptors have seven transmembrane domains and activate intracellular signaling pathways through G proteins.

4. Tyrosine kinase receptors

Tyrosine kinase receptors are membrane-bound receptors that are activated by growth factors, such as insulin-like growth factor (IGF) and epidermal growth factor (EGF). These receptors have an intracellular tyrosine kinase domain that phosphorylates specific tyrosine residues upon hormone binding, initiating downstream signaling events.

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5. Nuclear receptors

Nuclear receptors are a class of intracellular receptors that directly regulate gene expression. They bind to specific DNA sequences called hormone response elements (HREs) and act as transcription factors, either activating or repressing the transcription of target genes. Examples of nuclear receptors include the estrogen receptor and the glucocorticoid receptor.

Understanding the different types of hormone receptors is essential for comprehending the complex mechanisms by which hormones regulate various physiological processes in the body.

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Keywords: receptors, hormone, hormones, signaling, intracellular, membrane, growth, receptor, tyrosine