Name: how enzyme-linked receptors signal
Uploaded: 2021-04-07T12:11:59.000Z
Duration: 1 min 13 s
Channel: JoVE

Enzyme-linked receptors are transmembrane proteins that act as both receptors and enzymes, catalyzing intracellular reactions.One major family of enzyme-linked receptors is receptor tyrosine kinases, or RTKs.When a signaling molecule, called a ligand, binds to the extracellular domain of RTKs, two receptor molecules dimerize, or join together, within the membrane.Dimerization activates the tyrosine kinase domains on the cytoplasmic tails of the receptors.Each RTK in the dimer transfers phosphate groups from ATP to specific tyrosine residues on the opposing receptor. This process is called trans-autophosphorylation.The phosphorylated tyrosines act as docking sites for intracellular relay proteins. These proteins bind to specific phosphotyrosines, become activated, and start downstream signal transduction pathways that produce diverse cellular responses.

enzyme-linked receptors

Enzyme-linked Receptors

Enzyme-linked receptors are proteins that act as both receptor and enzyme, activating multiple intracellular signals. This is a large group of receptors that include the receptor tyrosine kinase (RTK) family. Many growth factors and hormones bind to and activate the RTKs.Neurotrophin (NT) receptors are a family of RTKs, including trkA, trkB, and trkC (tropomyosin-related kinase) receptors. TrkA is specific for nerve growth factor (NGF), neurotrophin-6, and neurotrophin-7. TrkB binds brain-derived neurotrophic factor (BDNF) and neurotrophin-4/5, while TrkC is specific for neurotrophin-3.The Trk receptors have a single transmembrane domain, with a growth factor binding site on the extracellular portion and an enzyme activation site intracellularly. Trk receptors can be monomeric or dimerized, where two Trk receptors are linked. Either a single growth factor binds two monomeric receptors causing them to dimerize, or the growth factor binds both sites on a pre-dimerized receptor to activate the receptor.Once the receptors are bound, the activated tyrosine kinases cross-phosphorylate the tyrosines using phosphate from ATP and donating them to each other. Phosphorylated tyrosines are recognized as docking sites by intracellular signaling protein domains, such as the Src homology 2 (SH2). Each docking site is used by different signaling proteins, which increases the variety of downstream effects regulated by these receptors.The interaction between NGF and TrkA has garnered attention for its role in the progression of Alzheimer&#x27;s disease, a disorder in which neurons develop amyloid plaques. Amyloid-beta is a cytotoxic fragment of the amyloid precursor protein (APP). It is hypothesized that binding NGF to the TrkA receptor decreases the generation of amyloid-beta by joining APP to the TrkA receptor. This eliminates the ability of beta-secretase 1 (BACE1) to cleave APP into amyloid-beta. Furthermore, the TrkA receptor can shuttle APP to the Golgi, where BACE1 enzymes are rare. In the brain of Alzheimer&#x27;s patients, there is a decreased generation of TrkA/APP complex in areas critical to learning and memory, like the hippocampus.

Enzyme-linked receptors are proteins that act as both receptor and enzyme, activating multiple intracellular signals. This is a large group of receptors ...

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JoVE Core

Molecular Biology

Unit 2

Cell Signaling Pathways

KEY TERMS AND CONCEPTS

how enzyme-linked receptors signal

Enzyme-linked receptors help cells respond to signals outside the cell. They are a major class of cell-surface receptors, and they work by triggering enzyme activity after a signal binds.

Many enzyme-linked receptors are receptor tyrosine kinases. When a signaling molecule binds, the receptor changes shape and activates its enzyme side. This starts a signaling step inside the cell that can affect cell behavior.

These receptors are important in cell communication. They help carry messages from the cell surface to the cell interior. That makes them a key part of how cells control growth, response, and other activities.

How Enzyme-Linked Receptors Signal

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Enzyme-linked receptors help cells respond to signals outside the cell. They are a major class of cell-surface receptors, and they work by triggering enzyme activity after a signal binds. Many enzyme-linked receptors are receptor tyrosine kinases. When a signaling molecule binds, the receptor changes shape and activates its enzyme side. This starts a signaling step inside the cell that can affect cell behavior. These receptors are important in cell communication. They help carry messages from...

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key terms and concepts

Explore how enzyme-linked receptors act at the cell surface and trigger enzyme activity to pass signals into the cell for communication and response.

How Enzyme-Linked Receptors Signal | JoVE K12

molecular biology

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How Enzyme-Linked Receptors Signal

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