Glycerol kinase is a phosphotransferase

Phosphotransferase

Phosphotransferases are a category of enzymes that catalyze phosphorylation reactions. The general form of the reactions they catalyze is: A—P + B ⇔ B—P + A...

 enzyme

Enzyme

Enzymes are proteins that catalyze chemical reactions. In enzymatic reactions, the molecules at the beginning of the process, called substrates, are converted into different molecules, called products. Almost all chemical reactions in a biological cell need enzymes in order to occur at rates...

 involved in triglyceride

Triglyceride

A triglyceride is an ester derived from glycerol and three fatty acids. There are many triglycerides, depending on the oil source, some are highly unsaturated, some less so....

s and glycerophospholipid

Glycerophospholipid

Glycerophospholipids or phosphoglycerides are glycerol-based phospholipids. They are the main component of biological membranes.-Structures:...

s synthesis.

Glycerol kinase catalyzes the transfer of a phosphate from ATP

Adenosine triphosphate

Adenosine-5'-triphosphate is a multifunctional nucleoside triphosphate used in cells as a coenzyme. It is often called the "molecular unit of currency" of intracellular energy transfer. ATP transports chemical energy within cells for metabolism...

 to glycerol

Glycerol

Glycerol is a simple polyol compound. It is a colorless, odorless, viscous liquid that is widely used in pharmaceutical formulations. Glycerol has three hydroxyl groups that are responsible for its solubility in water and its hygroscopic nature. The glycerol backbone is central to all lipids...

 thus forming glycerol phosphate (ATP + glycerol <=> ADP + sn-glycerol 3-phosphate). Adipocytes lack glycerol kinase so they cannot metabolize the glycerol produced during triacyl glycerol degradation. This glycerol is instead shuttled to the liver

Liver

The liver is a vital organ present in vertebrates and some other animals. It has a wide range of functions, including detoxification, protein synthesis, and production of biochemicals necessary for digestion...

 via the blood

Blood

Blood is a specialized bodily fluid in animals that delivers necessary substances such as nutrients and oxygen to the cells and transports metabolic waste products away from those same cells....

 where it is:

• phosphorylated by glycerol kinase to glycerol phosphate
• converted to DHAP (dihydroxyacetone phosphate) which can participate in glycolysis
  Glycolysis
  Glycolysis is the metabolic pathway that converts glucose C6H12O6, into pyruvate, CH3COCOO− + H+...
  
   or gluconeogenesis
  Gluconeogenesis
  Gluconeogenesis is a metabolic pathway that results in the generation of glucose from non-carbohydrate carbon substrates such as lactate, glycerol, and glucogenic amino acids....
  
  .

Structure

Glycerol Kinase (alternative name, ATP:glycerol 3-phosphotransferase or Glycerokinase) adopts a ribonuclease H

RNase H

The enzyme RNase H is a non-specific endonuclease and catalyzes the cleavage of RNA via a hydrolytic mechanism. Members of the RNase H family can be found in nearly all organisms, from archaea to bacteria and eukaryota....

-like fold consisting of an alpha-beta 2-layer sandwich of CATH

CATH

The CATH Protein Structure Classification is a semi-automatic, hierarchical classification of protein domains published in 1997 by Christine Orengo, Janet Thornton and their colleagues....

family 3.30.420.40. , there were 20 structures of this protein in the PDB, most of which are homodimeric.