Phosphorylation usually occurs on serine, threonine, tyrosine and histidine residues in eukaryotic proteins.

SERINE phosphate is one of the most widespread of amino-acid phosphates found in living systems. The phosphodiester of serine, phosphatidylserine, is an important phospholipid found in cell membranes. Thus serine is probably the only amino-acid found incorporated both in the membrane lipids and membrane proteins.

Phosphorylated proteins mediate cell division, cellular differentiation, signal transduction and other key cellular signaling processes. Phosphorylation of serine residues on proteins is one of the keys to a cascade of reactions that are of great interest to many researchers.

The strong negative charge on a phosphate group changes the way a protein is shaped and how it interacts with water. A protein that normally doesn’t interact with water will become hydrophilic, water-friendly, when phosphorylated. This change results in modifications to a protein’s physical and biochemical properties.

It is one of three amino acid residues that are commonly phosphorylated by kinases during cell signaling in eukaryotes. Phosphorylated serine residues are often referred to as phosphoserine. Serine proteases are a common type of protease.

D-serine is used for schizophrenia, Parkinson disease, and memory and thinking skills (cognitive function), and many other conditions. L-serine is used to improve sleeping, Lou Gehrig’s disease (amyotrophic lateral sclerosis or ALS), and many other conditions.

While L-glutamine supplementation is usually considered safe for most people, there are some who should avoid it. People with kidney disease, liver disease or Reye’s syndrome, a severe condition that can cause swelling of the liver and brain, should avoid taking L-glutamine supplements.

Phosphoserine (abbreviated as SEP or J) is an ester of serine and phosphoric acid. Phosphoserine is a component of many proteins as the result of posttranslational modifications. The phosphorylation of the alcohol functional group in serine to produce phosphoserine is catalyzed by various types of kinases.

kinase
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.

Phosphorylation is the addition of a phosphate group ( PO3−4 ) to a molecule, usually a protein. Phosphate has significant mass and charge, therefore it can change the folding (conformation) of the protein it attaches to (see image below). Kinases are the enzymes that transfer a phosphate group to a molecule.

L-serine is an amino acid essential for the synthesis of phosphatidylserine, which is a component of the membrane of brain cells (i.e., neurons). It can be produced in the body, including the brain, but an external supply from the diet is essential in maintaining necessary levels.

Protein serine/threonine phosphatase. Serine and threonine are amino acids which have similar side-chain compositions that contain a hydroxyl group and thus can be phosphorylated by enzymes called serine/threonine protein kinases. The addition of the phosphate group can be reversed by enzymes called serine/threonine phosphatases.

pKa Values INDEX Inorganic 2 Phenazine 24 Phosphates 3 Pyridine 25 Carboxylic acids 4, 8 Pyrazine 26 HCO3 10.33* HSe– 11.00* 77 H2CrO4 -0.98 30 H 2S 7.00* 77

Catalysis. The mechanisms of further effects may be divided into direct protein phosphorylation and protein synthesis: In direct protein phosphorylation, PKA directly either increases or decreases the activity of a protein. In protein synthesis, PKA first directly activates CREB, which binds the cAMP response element,…

Phosphodiesterase quickly converts cAMP to AMP, thus reducing the amount of cAMP that can activate protein kinase A. PKA is also regulated by a complex series of phosphorylation events, which can include modification by autophosphorylation and phosphorylation by regulatory kinases, such as PDK1. Thus, PKA is controlled, in part, by the levels cAMP.