Signal-transduction cascades mediate the sensing and processing of stimuli. These molecular circuits detect, amplify, and integrate diverse external signals to generate responses such as changes in enzyme activity, gene expression, or ion-channel activity.

In effect, signal transduction is said to have three stages:

• First, reception, whereby the signal molecule binds the receptor.
• Then, signal transduction, which is where the chemical signal results in a series of enzyme activations.
• Finally, the response, which is the resulting cellular responses.

Signal transduction pathways regulate many important cellular functions such as growth, differentiation, metabolism, and survival. They bind to their corresponding growth factors, triggering the downstream signaling cascade.

Protein kinases are an important class of intracellular enzymes that play a crucial role in most signal transduction cascades, from controlling cell growth and proliferation to the initiation and regulation of immunological responses.

Protein kinases and phosphatases are enzymes catalysing the transfer of phosphate between their substrates. A protein kinase catalyses the transfer of -phosphate from ATP (or GTP) to its protein substrates while a protein phosphatase catalyses the transfer of the phosphate from a phosphoprotein to a water molecule.

Second messengers are molecules that relay signals received at receptors on the cell surface — such as the arrival of protein hormones, growth factors, etc. But in addition to their job as relay molecules, second messengers serve to greatly amplify the strength of the signal.

Protein kinases (PTKs) are enzymes that regulate the biological activity of proteins by phosphorylation of specific amino acids with ATP as the source of phosphate, thereby inducing a conformational change from an inactive to an active form of the protein.

In biochemistry, phosphorylases are enzymes that catalyze the addition of a phosphate group from an inorganic phosphate (phosphate+hydrogen) to an acceptor. They include allosteric enzymes that catalyze the production of glucose-1-phosphate from a glucan such as glycogen, starch or maltodextrin.

A protein kinase inhibitor is a type of enzyme inhibitor that can block the action of protein kinases. Protein kinases add a phosphate group to a protein in a process called phosphorylation, which can turn a protein on or off and therefore affect its level of activity and function.

Protein kinases activate enzymes by phosphorylating or adding phosphate groups to them. Protein phosphatases dephosphorylate or remove phosphate groups from enzymes, including protein kinases.

What is a protein kinase, and what is its role in a signal transduction pathway? A protein kinase is an enzyme that transfers a phosphate group from ATP to a protein, usually activating that protein (often a second type of protein kinase).

A protein kinase is an enzyme that adds a phosphate group to another protein. Protein kinases are often part of a phosphorylation cascade that transduces a signal. A second messenger is a small, nonprotein molecule or ion that rapidly diffuses and relays a signal throughout a cell.

The most common (and important) types of kinases are the protein kinases, where a protein is the substrate. These enzymes are crucial to eukaryotic cell signaling. Phosphorylation of a protein can: 1) Change the conformation of a protein to “activate”or “inactivate” its activity.

Protein Phosphatases & Kinases A phosphatase is an enzyme that removes a phosphate group from a protein. Together, these two families of enzymes act to modulate the activities of the proteins in a cell, often in response to external stimuli.

What is a protein phosphatase? Messenger molecules that travel only a short distance. It causes a specific G Protein involved in regulating salt and water secretion to become permanently activated.

Listen to pronunciation. (KY-nays) A type of enzyme (a protein that speeds up chemical reactions in the body) that adds chemicals called phosphates to other molecules, such as sugars or proteins. This may cause other molecules in the cell to become either active or inactive.

Kinase, an enzyme that adds phosphate groups (PO43−) to other molecules. A large number of kinases exist—the human genome contains at least 500 kinase-encoding genes. Included among these enzymes’ targets for phosphate group addition (phosphorylation) are proteins, lipids, and nucleic acids.

This test measures the amount of creatine kinase (CK) in the blood. CK is a type of protein, known as an enzyme. It is mostly found in your skeletal muscles and heart, with lesser amounts in the brain.

A kinase is an enzyme that attaches a phosphate group to a protein. A phosphatase is an enzyme that removes a phosphate group from a protein. Together, these two families of enzymes act to modulate the activities of the proteins in a cell, often in response to external stimuli.